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Glossary of Cancer Terms

P

P-32 A radioactive form of phosphorus used in the treatment of cancer.

p-value A statistics term. A measure of probability that a difference between groups during an experiment happened by chance. For example, a p-value of .01 (p = .01) means there is a 1 in 100 chance the result occurred by chance. The lower the p-value, the more likely it is that the difference between groups was caused by treatment.

p53 gene A tumor suppressor gene that normally inhibits the growth of tumors. This gene is altered in many types of cancer.

pacemaker An electronic device that is implanted in the body to monitor heart rate and rhythm. It gives the heart electrical stimulation when it does not beat normally. An artificial pacemaker runs on batteries and has long, thin wires that connect it to the heart. Also called artificial pacemaker and cardiac pacemaker.

Pacific valerian Valeriana officinalis. A plant whose roots are used as a sedative and to treat certain medical conditions. It is being studied as a way to improve sleep in cancer patients undergoing treatment. Also called valerian, garden valerian, Indian valerian, Mexican valerian, garden heliotrope, Valeriana officinalis and Valerianae radix.

pack year A way to measure the amount a person has smoked over a long period of time. It is calculated by multiplying the number of packs of cigarettes smoked per day by the number of years the person has smoked. For example, 1 pack year is equal to smoking 1 pack per day for 1 year, or 2 packs per day for half a year, and so on.

paclitaxel A drug used to treat breast cancer, ovarian cancer, and AIDS-related Kaposi’s sarcoma. It is also used together with another drug to treat non-small cell lung cancer. Paclitaxel is also being studied in the treatment of other types of cancer. It belongs to the family of drugs called mitotic inhibitors. Also called Taxol.

Paclitaxel (Albumin-Stabilized Nanoparticle Formulation) A drug used to treat breast cancer that has spread or that has come back within 6 months after chemotherapy. It is also being studied in the treatment of newly diagnosed breast cancer and other types of cancer. Paclitaxel (albumin-stabilized nanoparticle formulation) belongs to the family of drugs called mitotic inhibitors. Also called nanoparticle paclitaxel, protein-bound paclitaxel, Abraxane and ABI-007.

paclitaxel liposome A form of the anticancer drug paclitaxel that may have fewer side effects and work better than paclitaxel. It is being studied in the treatment of cancer. It belongs to the family of drugs called mitotic inhibitors. Also called LEP-ETU and PNU-93914.

paclitaxel poliglumex A form of the anticancer drug paclitaxel combined with a protein called poliglumex that may have fewer side effects and work better than paclitaxel. It is being studied in the treatment of breast cancer, ovarian cancer, lung cancer and other types of cancer. It belongs to the family of drugs called mitotic inhibitors. Also called paclitaxel polyglutamate, Xyotax and CT-2103.

paclitaxel polyglutamate A form of the anticancer drug paclitaxel combined with a protein called poliglumex that may have fewer side effects and work better than paclitaxel. It is being studied in the treatment of breast cancer, ovarian cancer, lung cancer and other types of cancer. It belongs to the family of drugs called mitotic inhibitors. Also called paclitaxel poliglumex, Xyotax and CT-2103.

Paget's disease of bone A chronic condition in which both the breakdown and regrowth of bone are increased. Paget's disease of bone occurs most frequently in the pelvic and leg bones, skull, and lower spine. It is most common in older individuals, and may lead to bone pain, deformities and fractures. Also called osteitis deformans.

Paget's disease of the nipple A form of breast cancer in which the tumor grows from ducts beneath the nipple onto the surface of the nipple. Symptoms commonly include itching and burning and an eczema-like condition around the nipple, sometimes accompanied by oozing or bleeding.

pain threshold The point at which a person becomes aware of pain.

PALA A substance that is being studied for its ability to increase the effectiveness of the anticancer drug fluorouracil.

palate The roof of the mouth. The front portion is bony (hard palate), and the back portion is muscular (soft palate).

palatine uvula The soft flap of tissue that hangs down at the back of the mouth (at the edge of the soft palate). Also called uvula.

palifermin A form of keratinocyte growth factor (KGF) that is made in the laboratory. KGF stimulates the growth of cells that line the surface of the mouth and intestinal tract. Palifermin is used to prevent and treat oral mucositis (mouth sores) caused by high-dose chemotherapy and radiation therapy in leukemia and lymphoma. It is also being studied in the prevention and treatment of oral mucositis and dysphagia (difficulty swallowing) in other types of cancer. Palifermin belongs to the family of drugs called recombinant human keratinocyte growth factors. Also called Kepivance.

palliation Relief of symptoms and suffering caused by cancer and other life-threatening diseases. Palliation helps a patient feel more comfortable and improves the quality of life, but does not cure the disease.

palliative care Care given to improve the quality of life of patients who have a serious or life-threatening disease. The goal of palliative care is to prevent or treat as early as possible the symptoms of the disease, side effects caused by treatment of the disease, and psychological, social and spiritual problems related to the disease or its treatment. Also called comfort care, supportive care and symptom management.

palliative therapy Treatment given to relieve the symptoms and reduce the suffering caused by cancer and other life-threatening diseases. Palliative cancer therapies are given together with other cancer treatments, from the time of diagnosis, through treatment, survivorship, recurrent or advanced disease and at the end of life.

palmar-plantar erythrodysesthesia A condition marked by pain, swelling, numbness, tingling or redness of the hands or feet. It sometimes occurs as a side effect of certain anticancer drugs. Also called hand-foot syndrome.

palpable disease A term used to describe cancer that can be felt by touch, usually present in lymph nodes, skin or other organs of the body such as the liver or colon.

palpation Examination by pressing on the surface of the body to feel the organs or tissues underneath.

pamidronate A drug that is used to treat hypercalcemia (too much calcium in the blood) and cancer that has spread to the bones. It belongs to the family of drugs called bisphosphonates.

panacea A cure-all.

Pancoast tumor A type of lung cancer that begins in the upper part of a lung and spreads to nearby tissues such as the ribs and vertebrae. Most Pancoast tumors are non-small cell cancers. Also called pulmonary sulcus tumor.

pancreas A glandular organ located in the abdomen. It makes pancreatic juices, which contain enzymes that aid in digestion, and it produces several hormones, including insulin. The pancreas is surrounded by the stomach, intestines and other organs.

pancreatectomy Surgery to remove all or part of the pancreas. In a total pancreatectomy, part of the stomach, part of the small intestine, the common bile duct, gallbladder, spleen and nearby lymph nodes also are removed.

pancreatic Having to do with the pancreas.

pancreatic cancer A disease in which malignant (cancer) cells are found in the tissues of the pancreas. Also called exocrine cancer.

pancreatic duct Part of a system of ducts in the pancreas. Pancreatic juices containing enzymes are released into these ducts and flow into the small intestine.

pancreatic endocrine cancer A rare cancer that forms in the islets of Langerhans cells (a type of cell found in the pancreas). Also called islet cell carcinoma.

pancreatic enzyme A protein secreted by the pancreas that aids in the digestion of food.

pancreatic juice Fluid made by the pancreas. Pancreatic juices contain proteins called enzymes that aid in digestion.

pancreatitis Inflammation of the pancreas. Chronic pancreatitis may cause diabetes and problems with digestion. Pain is the primary symptom.

panic Sudden extreme anxiety or fear that may cause irrational thoughts or actions. Panic may include rapid heart rate, flushing (a hot, red face), sweating and trouble breathing.

panitumumab A human monoclonal antibody that is being used to treat colorectal cancer that has spread to other parts of the body. It is used in patients whose disease has not gotten better during or after treatment with other anticancer drugs. It is also being studied in the treatment of other types of cancer. Monoclonal antibodies are made in the laboratory and can locate and bind to cancer cells. Panitumumab binds to the epidermal growth factor receptor (EGFR) and may block tumor cell growth. Also called ABX-EGF and Vectibix.

PAP Prostatic acid phosphatase. An enzyme produced by the prostate. It may be found in increased amounts in men who have prostate cancer. Also called prostatic acid phosphatase.

Pap smear A procedure in which cells are scraped from the cervix for examination under a microscope. It is used to detect cancer and changes that may lead to cancer. A Pap smear can also show noncancerous conditions, such as infection or inflammation. Also called a Pap test.

Pap test A procedure in which cells are scraped from the cervix for examination under a microscope. It is used to detect cancer and changes that may lead to cancer. A Pap test can also show noncancerous conditions, such as infection or inflammation. Also called a Pap smear.

papillary serous carcinoma An aggressive cancer that usually affects the uterus/endometrium, peritoneum or ovary.

papillary thyroid cancer Cancer that forms in cells in the thyroid and grows in small finger-like shapes. It grows slowly, is more common in women than in men, and often occurs before age 40. It is the most common type of thyroid cancer.

papillary tumor A tumor shaped like a small mushroom, with its stem attached to the epithelial layer (inner lining) of an organ.

papilledema Swelling around the optic disk, the area where the optic nerve (the nerve that carries messages from the eye to the brain) enters the eyeball. Papilledema occurs when increased brain pressure caused by tumors or other problems results in swelling of the optic nerve.

paracentesis A procedure in which a thin needle or tube is put into the abdomen to remove fluid from the peritoneal cavity (the space within the abdomen that contains the intestines, the stomach and the liver).

paraganglia A collection of cells that came from embryonic nervous tissue, and are found near the adrenal glands and some blood vessels and nerves. Most paraganglia secrete epinephrine and norepinephrine.

paraganglioma A rare, usually benign tumor that develops from cells of the paraganglia. Paraganglia are a collection of cells that came from embryonic nervous tissue, and are found near the adrenal glands and some blood vessels and nerves. Paragangliomas that develop in the adrenal gland are called pheochromocytomas. Those that develop outside of the adrenal glands near blood vessels or nerves are called glomus tumors or chemodectomas.

parageusia A bad taste in the mouth. Also called dysgeusia.

paralysis Loss of ability to move all or part of the body.

paramyxovirus A type of virus that has hemagglutinin-neuraminidase proteins in the outer coat and RNA as the genetic material. Measles (rubeola) virus, mumps virus and Newcastle disease virus are paramyxoviruses.

paranasal sinus One of many small hollow spaces in the bones around the nose. Paranasal sinuses are named after the bones that contain them: frontal (the lower forehead), maxillary (cheekbones), ethmoid (beside the upper nose), and sphenoid (behind the nose). The paranasal sinuses open into the nasal cavity (space inside the nose) and are lined with cells that make mucus to keep the nose from drying out during breathing.

paranasal sinus and nasal cavity cancer Cancer that forms in tissues of the paranasal sinuses (small hollow spaces in the bones around the nose) or nasal cavity (the inside of the nose). The most common type of paranasal sinus and nasal cavity cancer is squamous cell carcinoma (cancer that begins in flat cells lining these tissues and cavities).

paraneoplastic syndrome A group of symptoms that may develop when substances released by some cancer cells disrupt the normal function of surrounding cells and tissue.

paranoia A mental disorder in which a person has an extreme fear and distrust of others. A paranoid person may have delusions that people are trying to harm him or her.

parasite An animal or plant that gets nutrients by living on or in an organism of another species. A complete parasite gets all of its nutrients from the host organism, but a semi-parasite gets only some of its nutrients from the host.

parasitic Having to do with or being a parasite (an animal or plant that gets nutrients by living on or in an organism of another species).

parasomnia An abnormal disruption of sleep, such as sleep walking, sleep talking, nightmares, bedwetting, sleep apnea (problems with breathing that cause loud snoring) or nighttime seizures.

parasympathetic nervous system The part of the nervous system that slows the heart, dilates blood vessels, decreases pupil size, increases digestive juices and relaxes muscles in the gastrointestinal tract.

parathormone A substance made by the parathyroid gland that helps the body store and use calcium. A higher-than-normal amount of parathormone causes high levels of calcium in the blood and may be a sign of disease. Also called parathyroid hormone, parathyrin and PTH.

parathyrin A substance made by the parathyroid gland that helps the body store and use calcium. A higher-than-normal amount of parathyrin causes high levels of calcium in the blood and may be a sign of disease. Also called parathormone, parathyroid hormone and PTH.

parathyroid cancer A rare cancer that forms in tissues of one or more of the parathyroid glands (four pea-sized glands in the neck that make parathyroid hormone, which helps the body store and use calcium).

parathyroid gland One of four pea-sized glands found on the thyroid. The parathyroid hormone produced by these glands increases the calcium level in the blood.

parathyroid hormone A substance made by the parathyroid gland that helps the body store and use calcium. A higher-than-normal amount of parathyroid hormone causes high levels of calcium in the blood and may be a sign of disease. Also called parathormone, parathyrin and PTH.

parathyroidectomy Surgery to remove one or more parathyroid glands (four pea-sized organs found on the thyroid).

parenchyma The essential or functional elements of an organ.

parenteral nutrition A form of nutrition that is delivered into a vein. Parenteral nutrition does not use the digestive system. It may be given to people who are unable to absorb nutrients through the intestinal tract because of vomiting that won't stop, severe diarrhea, or intestinal disease. It may also be given to those undergoing high-dose chemotherapy or radiation and bone marrow transplantation. It is possible to give all of the protein, calories, vitamins and minerals a person needs using parenteral nutrition. Also called hyperalimentation, total parenteral nutrition and TPN.

paresthesia An abnormal touch sensation, such as burning or prickling, that occurs without an outside stimulus.

paricalcitol A substance that is being used to treat overactive parathyroid glands in patients with kidney failure. It is also being studied in the treatment of cancer. Paricalcitol belongs to the family of drugs called vitamin D analogs.

parietal pericardium The outer layer of the pericardium, which is a thin sac of tissue that surrounds the heart.

parietal peritoneum The layers of tissue that line the abdominal wall and the pelvic cavity.

Parkinson's disease A progressive disorder of the nervous system marked by muscle tremors, muscle rigidity, decreased mobility, stooped posture, slow voluntary movements and a mask-like facial expression.

parotid gland cancer Cancer that forms in a parotid gland, the largest of the salivary glands, which make saliva and release it into the mouth. There are 2 parotid glands, one in front of and just below each ear. Most salivary gland tumors begin in parotid glands.

parotidectomy Surgery to remove all or part of the parotid gland (a large salivary gland located in front of and just below the ear). In a radical parotidectomy, the entire gland is removed.

paroxetine hydrochloride A drug used to treat depression and anxiety disorders. It belongs to the family of drugs called selective serotonin reuptake inhibitors (SSRI). Also called Paxil.

paroxysmal nocturnal hemoglobinuria PNH. A rare disorder in which red blood cells are easily destroyed by certain immune system proteins. Symptoms include blood clots, and red or brownish urine in the morning. Aplastic anemia (decreased production of blood cells) may lead to PNH, and people with PNH are at increased risk of acute myelogenous leukemia. Also called PNH.

partial cystectomy The removal of the cancer as well as some of the bladder tissue around the tumor. Also called segmental cystectomy.

partial hysterectomy Surgery to remove the uterus only. When the uterus and part or all of the cervix are removed, it is called a total hysterectomy.

partial laryngectomy An operation to remove part of the larynx (voice box).

partial mastectomy The removal of cancer as well as some of the breast tissue around the tumor and the lining over the chest muscles below the tumor. Usually some of the lymph nodes under the arm are also taken out. Also called segmental mastectomy.

partial nephrectomy Surgery to remove part of one kidney or a kidney tumor, but not an entire kidney.

partial oophorectomy Surgery to remove part of one ovary or part of both ovaries.

partial remission A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment. Also called partial response.

partial response A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment. Also called partial remission.

partial vulvectomy Surgery to remove most, but not all, of the vulva (the external female genital organs, including the clitoris, vaginal lips and the opening to the vagina).

passive antibody therapy Treatment with injections of antibodies made in another animal or in the laboratory.

pastoral counselor A person who is trained to give spiritual and mental health advice.

patchouli A bushy herb that is a member of the mint family. A strong-smelling oil taken from the leaves is used in perfumes, incense, detergents and hair conditioners. It has been used in some cultures to prevent disease. The scientific name is Pogostemon cablin

Paterson-Kelly syndrome A disorder marked by anemia caused by iron deficiency, and a web-like growth of membranes in the throat that makes swallowing difficult. Having Paterson-Kelly syndrome may increase the risk of developing esophageal cancer. Also called Plummer-Vinson syndrome and sideropenic dysphagia.

pathognomonic Having to do with a sign or symptom that is specific to a certain disease.

pathologic fracture A broken bone caused by disease, often by the spread of cancer to the bone.

pathological staging A method used to determine the stage of cancer. Tissue samples are removed during surgery or a biopsy. The stage is determined based on how the cells in the samples look under a microscope.

pathologist A doctor who identifies diseases by studying cells and tissues under a microscope.

pathology report The description of cells and tissues made by a pathologist based on microscopic evidence, and sometimes used to make a diagnosis of a disease.

patient advocate A person who helps a patient work with others who have an effect on the patient's health, including doctors, insurance companies, employers, case managers and lawyers. A patient advocate helps resolve issues about health care, medical bills, and job discrimination related to a patient's medical condition. Cancer advocacy groups try to raise public awareness about important cancer issues, such as the need for cancer support services, education and research. Such groups work to bring about change that will help cancer patients and their families.

patient-controlled analgesia PCA. A method of pain relief in which the patient controls the amount of pain medicine that is used. When pain relief is needed, the person can receive a preset dose of pain medicine by pressing a button on a computerized pump that is connected to a small tube in the body. Also called PCA.

Paxil A drug used to treat depression and anxiety disorders. It belongs to the family of drugs called selective serotonin reuptake inhibitors (SSRI). Also called paroxetine hydrochloride.

pazopanib A substance being studied in the treatment of cancer. It is a type of protein tyrosine kinase inhibitor and angiogenesis inhibitor. Also called GW786034 and pazopanib hydrochloride.

pazopanib hydrochloride A substance being studied in the treatment of cancer. It is a type of protein tyrosine kinase inhibitor and angiogenesis inhibitor. Also called pazopanib and GW786034.

PCA Patient-controlled analgesia. A method of pain relief in which the patient controls the amount of pain medicine that is used. When pain relief is needed, the person can receive a preset dose of pain medicine by pressing a button on a computerized pump that is connected to a small tube in the body. Also called patient-controlled analgesia.

PCNSL Primary CNS lymphoma. Cancer that forms in the lymph tissue of the brain, spinal cord, meninges (outer covering of the brain), or eye (called ocular lymphoma). Also called primary CNS lymphoma and primary central nervous system lymphoma.

PCOS Polycystic ovary syndrome. A condition marked by infertility, enlarged ovaries, menstrual problems, high levels of male hormones, excess hair on the face and body, acne, and obesity. Women with PCOS have an increased risk of diabetes, high blood pressure, heart disease and endometrial cancer. Also called polycystic ovary syndrome.

PCR Polymerase chain reaction. A laboratory method used to make many copies of a specific DNA sequence. Also called polymerase chain reaction.

PDQ Physician Data Query. PDQ is an online database developed and maintained by the National Cancer Institute. Designed to make the most current, credible, and accurate cancer information available to health professionals and the public, PDQ contains peer-reviewed summaries on cancer treatment, screening, prevention, genetics, complementary and alternative medicine, and supportive care; a registry of cancer clinical trials from around the world; and directories of physicians, professionals who provide genetics services and organizations that provide cancer care. Most of this information, and more specific information about PDQ, can be found on the NCI's Web site at http://www.cancer.gov/cancertopics/pdq. Also called Physician Data Query.

peau d'orange A dimpled condition of the skin of the breast, resembling the skin of an orange, sometimes found in inflammatory breast cancer.

pediatric Having to do with children.

pediatric hematologist A doctor who specializes in treating blood disorders in children.

pediatric nurse specialist A registered nurse with an advanced degree in nursing who specializes in the care of children.

pediatric surgeon A surgeon who specializes in the treatment of children. A surgeon removes or repairs a part of the body by operating on the patient.

pedigree A record of one's ancestors, offspring, siblings and their offspring that may be used to determine the pattern of certain genes or disease inheritance within a family.

PEG-asparaginase A form of the drug asparaginase that is used together with other anticancer drugs to treat acute lymphoblastic leukemia (ALL). It belongs to the family of drugs called enzymes. Also called pegaspargase and Oncaspar.

PEG-interferon alfa-2a A drug used to treat hepatitis C infections. It is also being studied in the treatment and prevention of cancer. It is a cytokine that is modified in the laboratory. It belongs to the family of drugs called biological response modifiers. Also called Pegasys.

PEG-interferon alfa-2b A drug used to treat hepatitis C infections. It is also being studied in the treatment and prevention of cancer. It is a cytokine that is modified in the laboratory. It belongs to the family of drugs called biological response modifiers. Also called PEG-Intron and SCH 54031.

PEG-Intron A drug used to treat hepatitis C infections. It is also being studied in the treatment and prevention of cancer. It is a cytokine that is modified in the laboratory. It belongs to the family of drugs called biological response modifiers. Also called PEG-interferon alfa-2b and SCH 54031.

PEG-MGDF A form of megakaryocyte growth and development factor (MGDF) that is made in the laboratory. MGDF comes from the protein thrombopoietin, which is normally made in the body to help make platelets. PEG-MGDF is being studied as a way to increase the number of platelets in patients receiving chemotherapy. Also called polyethylene glycosylated recombinant human megakaryocyte growth and development factor and PEG-rhMGDF.

PEG-rhMGDF Polyethylene glycosylated recombinant human megakaryocyte growth and development factor. A form of megakaryocyte growth and development factor (MGDF) that is made in the laboratory. MGDF comes from the protein thrombopoietin, which is normally made in the body to help make platelets. PEG-rhMGDF is being studied as a way to increase the number of platelets in patients receiving chemotherapy. Also called PEG-MGDF and polyethylene glycosylated recombinant human megakaryocyte growth and development factor.

pegaspargase A form of the drug asparaginase that is used together with other anticancer drugs to treat acute lymphoblastic leukemia (ALL). It belongs to the family of drugs called enzymes. Also called PEG-asparaginase and Oncaspar.

Pegasys A drug used to treat hepatitis C infections. It is also being studied in the treatment and prevention of cancer. It is a cytokine that is modified in the laboratory. It belongs to the family of drugs called biological response modifiers. Also called PEG-interferon alfa-2a.

pegfilgrastim A drug used to increase numbers of white blood cells in patients who are receiving chemotherapy. It belongs to the family of drugs called colony-stimulating factors. Also called Neulasta and filgrastim-SD/01.

pegylated liposomal doxorubicin A form of the anticancer drug doxorubicin that may have fewer side effects and work better than doxorubicin. It is being studied in the treatment of ovarian cancer, breast cancer, Kaposi’s sarcoma, and other types of cancer. It is a type of anthracycline antitumor antibiotic. Also called liposomal doxorubicin, doxorubicin hydrochloride pegylated liposomes, Caelyx and Doxil.

PEITC Phenethyl isothiocyanate. A substance being studied in the prevention of cancer. It is a naturally occurring compound found in some cruciferous vegetables. Also called phenethyl isothiocyanate.

peldesine A substance that is being studied for the treatment of cancer.

pelvic Having to do with the pelvis (the lower part of the abdomen located between the hip bones).

pelvic examination A physical examination in which the health care professional will feel for lumps or changes in the shape of the vagina, cervix, uterus, fallopian tubes, ovaries and rectum. The health care professional will also use a speculum to open the vagina to look at the cervix and take samples for a Pap test. Also called an internal examination.

pelvic exenteration Surgery to remove the lower colon, rectum, and bladder, and create stomata (openings) through which urine and stool are passed out of the body. In women, the cervix, vagina, ovaries and nearby lymph nodes are also removed.

pelvic lymphadenectomy Surgery to remove lymph nodes in the pelvis for examination under a microscope to see if they contain cancer.

pelvic wall The muscles and ligaments that line the part of the body between the hips.

pelvis The lower part of the abdomen, located between the hip bones.

pemetrexed disodium A drug that is used to treat malignant pleural mesothelioma and advanced non-small cell lung cancer and is being studied in the treatment of other types of cancer. It belongs to the family of drugs called enzyme inhibitors. Also called Alimta and LY231514

penclomedine A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called alkylating agents.

penectomy Surgery to remove part or all of the penis.

penicillamine A drug that removes copper from the body and is used to treat diseases in which there is an excess of copper. It is also being studied as a possible angiogenesis inhibitor in the treatment of brain tumors.

penicillin A drug that is used to treat infection. It belongs to the family of drugs called antibiotics.

penile cancer A rare cancer that forms in the penis (the external male reproductive organ). Most penile cancers are squamous cell carcinomas (cancer that begins in flat cells lining the penis).

penile implant A firm rod or inflatable device that is placed in the penis during a surgical procedure. The implant makes it possible to have and keep an erection. Penile implants are used to treat erectile dysfunction or impotence.

penis An external male reproductive organ. It contains a tube called the urethra, which carries semen and urine to the outside of the body.

pentetic acid calcium A drug that protects healthy tissues from the toxic effects of anticancer drugs.

pentosan polysulfate A drug used to relieve pain or discomfort associated with chronic inflammation of the bladder. It is also being evaluated for its protective effects on the gastrointestinal tract in people undergoing radiation therapy.

pentostatin An anticancer drug that belongs to the family of drugs called antimetabolites.

pentoxifylline A drug used to prevent blood clotting and as a treatment that may help decrease weight loss in people with cancer.

peptide Any compound consisting of two or more amino acids, the building blocks of proteins.

peptide 946 A protein that causes white blood cells to recognize and destroy melanoma cells.

percutaneous Passing through the skin; as in an injection or a topical medicine.

percutaneous ethanol injection An injection of ethanol (alcohol) through the skin directly into the tumor to kill cancer cells.

percutaneous transhepatic biliary drainage A procedure to drain bile to relieve pressure in the bile ducts caused by a blockage. An X-ray of the liver and bile ducts locates the blockage of bile flow. Images made by ultrasound guide placement of a stent (tube), which remains in the liver. Bile drains through the stent into the small intestine or into a collection bag outside the body. This procedure may relieve jaundice before surgery. Also called percutaneous transhepatic cholangiodrainage and PTCD.

percutaneous transhepatic cholangiodrainage PTCD. A procedure to drain bile to relieve pressure in the bile ducts caused by a blockage. An X-ray of the liver and bile ducts locates the blockage of bile flow. Images made by ultrasound guide placement of a stent (tube), which remains in the liver. Bile drains through the stent into the small intestine or into a collection bag outside the body. This procedure may relieve jaundice before surgery. Also called percutaneous transhepatic biliary drainage and PTCD.

percutaneous transhepatic cholangiography PTC. A procedure to X-ray the hepatic and common bile ducts. A contrasting agent is injected into the liver or bile duct, and the ducts are then X-rayed to find the point of obstruction. Also called PTC.

performance status A measure of how well a patient is able to perform ordinary tasks and carry out daily activities.

perfusion Bathing an organ or tissue with fluid. In regional perfusion, a specific area of the body (usually an arm or a leg) receives high doses of anticancer drugs through a blood vessel. Such a procedure is performed to treat cancer that has not spread.

perfusion magnetic resonance imaging A special type of magnetic resonance imaging (MRI) that uses an injected dye in order to see blood flow through tissues. Also called magnetic resonance perfusion imaging.

pericardial effusion An abnormal collection of fluid inside the sac that covers the heart.

perifosine A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called alkylphospholipids.

perillyl alcohol A substance that is being studied in the prevention of cancer. It belongs to the family of plant drugs called monoterpenes.

perimenopausal The time of a woman's life when menstrual periods become irregular. Refers to the time near menopause.

perineal colostomy An opening made surgically to allow the colon to exit the body through the perineum (the area of the body between the anus and the vulva in females, and between the anus and the scrotum in males). A colostomy provides a new path for waste material to leave the body after part of the colon has been removed.

perineal prostatectomy Surgery to remove the prostate through an incision made between the scrotum and the anus.

perineum The area of the body between the anus and the vulva in females, and between the anus and the scrotum in males.

perineural Around a nerve or group of nerves.

perioperative Around the time of surgery. This usually lasts from the time the patient goes into the hospital or doctor's office for surgery until the time the patient goes home.

peripheral blood Blood circulating throughout the body.

peripheral blood lymphocyte therapy A treatment for Epstein-Barr virus infection or overgrowth of white blood cells (lymphocytes) after an organ or bone marrow transplant. Specific lymphocytes from a sibling donor are infused into the patient to try and reverse these conditions.

peripheral blood smear A procedure in which a sample of blood is viewed under a microscope to count different circulating blood cells (red blood cells, white blood cells, platelets, etc.) and see whether the cells look normal.

peripheral neuropathy A condition of the nervous system that causes numbness, tingling, burning or weakness. It usually begins in the hands or feet, and can be caused by certain anticancer drugs.

peripheral primitive neuroectodermal tumor pPNET. A type of cancer that forms in bone or soft tissue. Also called pPNET and Ewing's sarcoma.

peripheral stem cell An immature cell found circulating in the bloodstream. New blood cells develop from peripheral stem cells.

peripheral stem cell support A method of replacing blood-forming cells destroyed by cancer treatment. Immature blood cells (stem cells) in the circulating blood that are similar to those in the bone marrow are given to the patient after treatment. This helps the bone marrow recover and continue producing healthy blood cells. Transplantation may be autologous (an individual's own blood cells saved earlier), allogeneic (blood cells donated by someone else), or syngeneic (blood cells donated by an identical twin). Also called peripheral stem cell transplantation.

peripheral stem cell transplantation A method of replacing blood-forming cells destroyed by cancer treatment. Immature blood cells (stem cells) in the circulating blood that are similar to those in the bone marrow are given to the patient after treatment. This helps the bone marrow recover and continue producing healthy blood cells. Transplantation may be autologous (an individual's own blood cells saved earlier), allogeneic (blood cells donated by someone else), or syngeneic (blood cells donated by an identical twin). Also called peripheral stem cell support.

peripheral T-cell lymphoma One of a group of aggressive (fast-growing) non-Hodgkin’s lymphomas that begin in mature T lymphocytes (T cells that have matured in the thymus gland and gone to other lymphatic sites in the body, including lymph nodes, bone marrow and spleen.) Also called mature T-cell lymphoma.

peripheral venous catheter A small, flexible tube used to deliver fluids into the body. A needle is used to insert the catheter into a vein, usually in the back of the hand or in the forearm. The tubing is then taped to the skin to hold it in place.

peristalsis The rippling motion of muscles in the intestine or other tubular organs characterized by the alternate contraction and relaxation of the muscles that propel the contents onward.

peritoneal Having to do with the parietal peritoneum (the tissue that lines the abdominal wall and pelvic cavity) and visceral peritoneum (the tissue that covers most of the organs in the abdomen, including the intestines).

peritoneal cancer Cancer of the tissue that lines the abdominal wall and covers organs in the abdomen.

peritoneal cavity The space within the abdomen that contains the intestines, the stomach, and the liver. It is bound by thin membranes.

peritoneal fluid A liquid that is made in the abdominal cavity to lubricate the surface of the tissue that lines the abdominal wall and pelvic cavity and covers most of the organs in the abdomen.

peritoneal infusion A method of delivering fluids and drugs directly into the abdominal cavity through a thin tube. Also called intraperitoneal infusion.

peritoneal perfusion A method of delivering fluids and drugs directly to tumors in the peritoneal cavity.

peritoneum The tissue that lines the abdominal wall and covers most of the organs in the abdomen.

peritonitis Inflammation of the peritoneum (tissue that lines the abdominal wall and covers most of the organs in the abdomen). Peritonitis can result from infection, injury, or certain diseases. Symptoms may include swelling of the abdomen, severe pain, and weight loss.

pernicious anemia A type of anemia (low red blood cell count) caused by the body's inability to absorb vitamin B12.

perturbation A disruption or disturbance.

pertussis A serious bacterial infection of the lungs and breathing tubes that spreads easily. Pertussis begins like a cold, but develops into severe coughing and gasping for air. Long spells of coughing may cause vomiting, and broken blood vessels in the eyes and on the skin. Also called whooping cough.

pertuzumab A monoclonal antibody that is being studied in the treatment of cancer. Monoclonal antibodies are produced in the laboratory and can locate and bind to cancer cells.

pesticide A chemical that is used to kill insects and other pests.

PET scan Positron emission tomography scan. A procedure in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the glucose is used. Because cancer cells often use more glucose than normal cells, the pictures can be used to find cancer cells in the body. Also called positron emission tomography scan.

petechiae Pinpoint, unraised, round red spots under the skin caused by bleeding.

Peutz-Jeghers syndrome PJS. A genetic disorder in which polyps form in the intestine and dark spots appear on the mouth and fingers. Having PJS increases the risk of developing gastrointestinal and many other types of cancer. Also called PJS.

PF-00299804 A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called protein tyrosine kinase inhibitors.

PF-3512676 A substance that is being studied in the treatment of some types of cancer. It belongs to the family of drugs called biological response modifiers. Also called CpG 7909 and ProMune.

PHA-739358 A substance being studied in the treatment of chronic myelogenous leukemia. PHA-739358 may stop tumor growth by blocking certain enzymes needed for cancer cells to divide and causing them to die. It is a type of kinase inhibitor.

phagocyte An immune system cell that can surround and kill microorganisms and remove dead cells. Phagocytes include macrophages.

phagocytosis The process by which a phagocyte (a type of white blood cell) surrounds and destroys foreign substances (such as bacteria) and removes dead cells.

phantom limb pain The sensation of pain or other unpleasant feelings in the place of a missing (phantom) limb.

pharmacokinetics The activity of drugs in the body over a period of time, including the processes by which drugs are absorbed, distributed in the body, localized in the tissues and excreted.

pharmacology The study of the origin, chemistry and uses of drugs and their effects on the body.

pharmacopoeia A book describing chemicals, drugs, and other substances and how they are used as medicines. It is prepared by a recognized authority.

pharyngeal cancer Cancer that forms in tissues of the pharynx (the hollow tube inside the neck that starts behind the nose and ends at the top of the windpipe and esophagus). Pharyngeal cancer includes cancer of the nasopharynx (the upper part of the throat behind the nose), the oropharynx (the middle part of the pharynx), and the hypopharynx (the bottom part of the pharynx). Cancer of the larynx (voice box) may also be included as a type of pharyngeal cancer. Most pharyngeal cancers are squamous cell carcinomas (cancer that begins in thin, flat cells that look like fish scales). Also called throat cancer.

pharynx The hollow tube inside the neck that starts behind the nose and ends at the top of the trachea (windpipe) and esophagus (the tube that goes to the stomach). The pharynx is about 5 inches long, depending on body size. Also called the throat.

phase I detoxification A process in which the liver uses one of two major enzyme pathways to change a toxic substance, such as an anticancer drug, into a less toxic substance that is easier for the body to excrete.

phase I trial The first step in testing a new treatment in humans. These studies test the best way to give a new treatment (for example, by mouth, intravenous infusion or injection) and the best dose. The dose is usually increased a little at a time in order to find the highest dose that does not cause harmful side effects. Because little is known about the possible risks and benefits of the treatments being tested, phase I trials usually include only a small number of patients who have not been helped by other treatments.

phase I/II trial A trial to study the safety, dosage levels and response to a new treatment.

phase II detoxification A process in which the liver uses one of two major enzyme pathways to change a toxic substance, such as an anticancer drug, into a less toxic substance that is easier for the body to excrete. In phase II detoxification, liver cells add a substance (such as cysteine, glycine, or a sulfur molecule) to a toxic chemical or drug, to make it less harmful.

phase II trial A study to test whether a new treatment has an anticancer effect (for example, whether it shrinks a tumor or improves blood test results) and whether it works against a certain type of cancer.

phase II/III trial A trial to study response to a new treatment and the effectiveness of the treatment compared with the standard treatment regimen.

phase III trial A study to compare the results of people taking a new treatment with the results of people taking the standard treatment (for example, which group has better survival rates or fewer side effects). In most cases, studies move into phase III only after a treatment seems to work in phases I and II. Phase III trials may include hundreds of people.

phase IV trial After a treatment has been approved and is being marketed, it is studied in a phase IV trial to evaluate side effects that were not apparent in the phase III trial. Thousands of people are involved in a phase IV trial.

phenethyl isothiocyanate PEITC. A substance being studied in the prevention of cancer. It is a naturally occurring compound found in some cruciferous vegetables. Also called PEITC.

phenobarbital A drug that is used to treat seizures and as a sedative. It is being studied in the treatment of diarrhea and for its ability to increase the antitumor effect of other therapies. It belongs to the family of drugs called barbiturates.

phenol A very poisonous chemical substance made from tar and also found in some plants and essential oils (scented liquid taken from plants). Phenol is used to make plastics, nylon, epoxy, medicines and to kill germs. Also called carbolic acid.

phenothiazine A type of drug that is used to treat severe mental and emotional disorders, severe nausea and vomiting, and certain other conditions. It belongs to the families of drugs called antipsychotics and antiemetics.

phenoxodiol A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called signal transduction inhibitors.

phenylacetate A substance that is being studied in the treatment of cancer.

phenylbutyrate A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called differentiating agents.

phenylketonuria PKU. An inherited disorder that causes a build-up of phenylalanine (an amino acid) in the blood. This can cause mental retardation, behavioral and movement problems, seizures, and delayed development. Using a blood test, PKU can easily be found in newborns, and treatment is a diet low in phenylalanine. Also called PKU.

pheochromocytoma Tumor that forms in the center of the adrenal gland (gland located above the kidney) that causes it to make too much adrenaline. Pheochromocytomas are usually benign (noncancerous) but can cause high blood pressure, pounding headaches, heart palpitations, flushing of the face, nausea and vomiting.

pheresis A procedure in which blood is collected, part of the blood such as platelets or white blood cells is taken out, and the rest of the blood is returned to the donor. Also called apheresis.

Philadelphia chromosome An abnormality of chromosome 22 in which part of chromosome 9 is transferred to it. Bone marrow cells that contain the Philadelphia chromosome are often found in chronic myelogenous leukemia.

philosophical Having to do with the deeper questions of life and with a person’s basic beliefs, ideas and attitudes.

phlebotomy The puncture of a vein with a needle for the purpose of drawing blood. Also called venipuncture.

phlegm A more than normal amount of thick mucus made by the cells lining the upper airways and lungs. A buildup of phlegm may be caused by infection, irritation or chronic lung disease, and can cause discomfort in the chest and coughing.

phobia An extreme, irrational, fear of something that may cause a person to panic. Examples of common phobias include fear of spiders, flying in an airplane, elevators, heights, enclosed rooms, crowded public places and embarrassing oneself in front of other people.

phospholipid A lipid (fat) that contains phosphorus. Phospholipids are a major part of cell membranes.

phospholipid complex A chemical or drug that is attached to a lipid (fat) that contains phosphorus.

phosphoric Having to do with or containing the element phosphorus.

phosphorus A nonmetallic element that is found in the blood, muscles, nerves, bones, and teeth and is a component of adenosine triphosphate (ATP; the primary energy source for the body's cells).

phosphorus-32 A radioactive form of phosphorus used in the treatment of cancer. It is also used to help locate areas of DNA damage.

photoactivity The effect produced when certain substances are exposed to light. In cancer treatment, some drugs become active when exposed to light and are then able to kill tumor cells.

photodynamic therapy Treatment with drugs that become active when exposed to light. These drugs kill cancer cells.

Photofrin A drug used to treat some types of cancer. When absorbed by cancer cells and exposed to light, Photofrin becomes active and kills the cancer cells. It belongs to the family of drugs called photodynamic therapy agents. Also called porfimer sodium.

photon-beam radiation A type of radiation therapy that reaches deep tumors with high-energy X-rays made by a machine called a linear accelerator.

photopheresis A procedure in which blood is removed from the body and treated with ultraviolet light and drugs that become active when exposed to light. The blood is then returned to the body. It is being studied in the treatment of some blood and bone marrow diseases and graft-vs-host disease (GVHD). Also called extracorporeal photopheresis.

photophobia A condition in which the eyes are more sensitive than normal to light.

photosensitizer A drug used in photodynamic therapy. When absorbed by cancer cells and exposed to light, the drug becomes active and kills the cancer cells. Also called photosensitizing agent.

photosensitizing agent A drug used in photodynamic therapy. When absorbed by cancer cells and exposed to light, the drug becomes active and kills the cancer cells. Also called photosensitizer.

phototoxicity A condition in which the skin or eyes become very sensitive to sunlight or other forms of light. It can be caused by taking certain drugs, or rubbing certain essential oils (scented liquid taken from plants) or other topical agents into the skin. Phototoxicity causes sunburn, blisters and other skin problems.

phyllodes tumor A type of tumor found in breast tissue. It is often large and bulky and grows quickly. It is usually benign (not cancer), but may be malignant (cancer). Also called cystosarcoma phyllodes.

physical dependence A condition in which a person takes a drug over time, and unpleasant physical symptoms occur if the drug is suddenly stopped or taken in smaller doses.

physical examination An exam of the body to check for general signs of disease.

physical therapist A health professional who teaches exercises and physical activities that help condition muscles and restore strength and movement.

physical therapy The use of exercises and physical activities to help condition muscles and restore strength and movement. For example, physical therapy can be used to restore arm and shoulder movement and build back strength after breast cancer surgery.

physician Medical doctor.

Physician Data Query PDQ. The Physician Data Query is an online database developed and maintained by the National Cancer Institute. Designed to make the most current, credible, and accurate cancer information available to health professionals and the public, PDQ contains peer-reviewed summaries on cancer treatment, screening, prevention, genetics, complementary and alternative medicine, and supportive care; a registry of cancer clinical trials from around the world; and directories of physicians, professionals who provide genetics services and organizations that provide cancer care. Most of this information and more specific information about PDQ can be found on the NCI's Web site at http://www.cancer.gov/cancertopics/pdq. Also called PDQ.

physiologic Having to do with the functions of the body. When used in the phrase "physiologic age," it refers to an age assigned by general health, as opposed to calendar age.

phytic acid A substance found in many foods that come from plants, including corn, wheat, rice, and soybeans, and in large amounts in cereals and legumes. It is being studied in the prevention of cancer. Also called inositol hexaphosphate and IP6.

phytochemical A substance found in plants. Some phytochemicals may reduce the risk of cancer.

phytoestrogen An estrogen-like substance found in some plants and plant products. Phytoestrogens may have anticancer effects.

phytohemagglutinin A substance found in plants that causes red blood cells to clump together and certain white blood cells to divide.

phytol A chemical substance that comes from plants and is used to make vitamins E and K. Phytol is also found in soaps, beauty care products and household products.

phytosterol A plant-based compound that can compete with dietary cholesterol to be absorbed by the intestines, resulting in lower blood cholesterol levels. Phytosterols may have some effect in cancer prevention. Also called plant sterol.

PI-88 A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called antiangiogenesis agents.

pigment A substance that gives color to tissue. Pigments are responsible for the color of skin, eyes and hair.

pilocarpine A drug used to increase salivation in people who have dry mouth caused by opioids or radiation therapy. Pilocarpine belongs to the family of drugs called alkaloids.

pilocytic Made up of cells that look like fibers when viewed under a microscope.

pilot study The initial study examining a new method or treatment.

PIN Prostatic intraepithelial neoplasia. Noncancerous growth of cells lining the internal and external surfaces of the prostate gland. Having high-grade PIN may increase the risk of developing prostate cancer. Also called prostatic intraepithelial neoplasia.

pineal body A tiny organ in the cerebrum that produces melatonin. Also called pineal gland or pineal organ.

pineal gland A tiny organ in the cerebrum that produces melatonin. Also called pineal body or pineal organ.

pineal organ A tiny organ in the cerebrum that produces melatonin. Also called pineal body or pineal gland.

pineal region tumor A type of brain tumor that occurs in or around the pineal gland, a tiny organ near the center of the brain.

pineoblastoma A fast-growing type of brain tumor that occurs in or around the pineal gland, a tiny organ near the center of the brain.

pineocytoma A slow-growing type of brain tumor that occurs in or around the pineal gland, a tiny organ near the center of the brain.

pinkeye A condition in which the conjunctiva (membranes lining the eyelids and covering the white part of the eye) become inflamed or infected. Also called conjunctivitis.

pioglitazone A drug that is used to treat type 2 diabetes and is being studied in the prevention of head and neck cancer. It may be able to stop leukoplakia (a precancerous condition affecting the mouth) from developing into cancer. It belongs to the family of drugs called thiazolidinediones. Also called Actos.

piperacillin-tazobactam A drug combination that is used to treat infection in people with cancer. Piperacillin is a synthetic penicillin; tazobactam enhances the effectiveness of piperacillin.

pirfenidone A substance that is being studied in the prevention and treatment of scar tissue caused by radiation therapy. It belongs to the family of drugs called anti-inflammatory agents.

Piritrexim A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called folate antagonists.

pituitary gland The main endocrine gland. It produces hormones that control other glands and many body functions, especially growth.

pituitary tumor A tumor that forms in the pituitary gland. The pituitary is a pea-sized organ in the center of the brain above the back of the nose. It makes hormones that affect other glands and many body functions, especially growth. Most pituitary tumors are benign (not cancer).

pixantrone A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called antitumor antibiotics. Also called BBR 2778.

PJS Peutz-Jeghers syndrome. A genetic disorder in which polyps form in the intestine and dark spots appear on the mouth and fingers. Having PJS increases the risk of developing gastrointestinal and many other types of cancer. Also called Peutz-Jeghers syndrome.

PKC Protein kinase C. An enzyme found throughout the body's tissues and organs. Several forms of PKC are involved in many cellular functions. PKC is being studied in the treatment of cancer. Also called protein kinase C.

PKC412 A substance that is being studied in the treatment of leukemia. It belongs to the family of drugs called protein kinase inhibitors. Also called N-benzoyl-staurosporine and midostaurin.

PKU Phenylketonuria. An inherited disorder that causes a build-up of phenylalanine (an amino acid) in the blood. This can cause mental retardation, behavioral and movement problems, seizures and delayed development. Using a blood test, PKU can easily be found in newborns, and treatment is a diet low in phenylalanine. Also called phenylketonuria.

placebo An inactive substance or treatment that looks the same as, and is given the same way as, an active drug or treatment being tested. The effects of the active drug or treatment are compared to the effects of the placebo.

placebo therapy An inactive treatment or procedure that is intended to mimic as closely as possible a therapy in a clinical trial. Also called sham therapy.

placebo-controlled Refers to a clinical study in which the control patients receive a placebo.

placenta The organ that nourishes the developing fetus in the uterus.

placental blood transplantation The transfer of blood from a placenta to an individual whose own blood production system is suppressed. Placental blood contains high levels of stem cells needed to produce new blood cells. It is being studied in the treatment of cancer and severe blood disorders such as aplastic anemia.

plant sterol A plant-based compound that can compete with dietary cholesterol to be absorbed by the intestines, resulting in lower blood cholesterol levels. Plant sterols may have some effect in cancer prevention. Also called phytosterol.

plaque In medicine, a small, abnormal patch of tissue on a body part or an organ. Plaques may also be a build-up of substances from a fluid, such as cholesterol in the blood vessels.

plasma The clear, yellowish, fluid part of the blood that carries the blood cells. The proteins that form blood clots are in plasma.

plasma cell A type of white blood cell that produces antibodies.

plasma cell myeloma A type of cancer that begins in plasma cells (white blood cells that produce antibodies). Also called multiple myeloma, Kahler’s disease or myelomatosis.

plasma cell tumor A tumor that begins in plasma cells (white blood cells that produce antibodies). Multiple myeloma, monoclonal gammopathy of undetermined significance (MGUS), and plasmacytoma are types of plasma cell tumors.

plasma membrane The outer membrane of a cell.

plasmacytic Having to do with plasma cells (a type of white blood cells).

plasmacytoma A type of cancer that begins in plasma cells (white blood cells that produce antibodies). A plasmacytoma may turn into multiple myeloma.

plasmapheresis The process of separating certain cells from the plasma in the blood by a machine; only the cells are returned to the person. Plasmapheresis can be used to remove excess antibodies from the blood.

plastic surgeon A surgeon who specializes in reducing scarring or disfigurement that may occur as a result of accidents, birth defects, or treatment for diseases.

plastic surgery An operation that restores or improves the appearance of body structures.

platelet A type of blood cell that helps prevent bleeding by causing blood clots to form. Also called a thrombocyte.

platinum A metal that is an important component of some anticancer drugs, such as cisplatin and carboplatin.

Plenaxis A drug used to reduce the amount of testosterone made in patients with advanced symptomatic prostate cancer for which no other treatment options are available. It belongs to the family of drugs called gonadotropin-releasing hormone (GnRH) antagonists. Also called abarelix.

pleomorphic Occurring in various distinct forms. In terms of cells, having variation in the size and shape of cells or their nuclei.

pleura A thin layer of tissue covering the lungs and lining the interior wall of the chest cavity. It protects and cushions the lungs. This tissue secretes a small amount of fluid that acts as a lubricant, allowing the lungs to move smoothly in the chest cavity while breathing.

pleural cavity The space enclosed by the pleura, which is a thin layer of tissue that covers the lungs and lines the interior wall of the chest cavity.

pleural effusion An abnormal collection of fluid between the thin layers of tissue (pleura) lining the lung and the wall of the chest cavity.

pleurodesis A medical procedure that uses chemicals or drugs to cause inflammation and adhesion between the layers of the pleura (the tissue that covers the lungs and lines the interior wall of the chest cavity). This prevents the buildup of fluid in the pleural cavity. It is used as a treatment for severe pleural effusion.

pleuropulmonary blastoma A rare and very aggressive (fast-growing) cancer that forms in tissues of the lung and pleura (a thin layer of tissue covering the lungs and the inside wall of the chest cavity). Pleuropulmonary blastoma is most common in children.

plexiform neurofibroma A nerve that has become thick and misshapen due to the abnormal growth of cells and tissues that cover the nerve.

plexopathy A disorder affecting a network of nerves, blood vessels or lymph vessels.

plicamycin A drug used to treat some types of testicular cancer, hypercalcemia (abnormally high levels of calcium in the blood), and hypercalciuria (abnormally high levels of calcium in the urine). It belongs to the families of drugs called antineoplastics and antibiotics. Also called Mithracin.

PLL Prolymphocytic leukemia. A type of chronic lymphocytic leukemia (CLL) in which too many immature white blood cells (prolymphocytes) are found in the blood and bone marrow. PLL usually progresses more rapidly than classic CLL. Also called prolymphocytic leukemia.

ploidy The number of sets of chromosomes in a cell or an organism. For example, haploid means one set and diploid means two sets.

Plummer-Vinson syndrome A disorder marked by anemia caused by iron deficiency, and a web-like growth of membranes in the throat that makes swallowing difficult. Having Plummer-Vinson syndrome may increase the risk of developing esophageal cancer. Also called Paterson-Kelly syndrome and sideropenic dysphagia.

pluripotent Able to mature or develop in any of several ways.

pluripotent stem cell A cell that is able to develop into several different types of cells or tissues in the body.

pM-81 A monoclonal antibody that is being studied in the detection and treatment of cancer. Monoclonal antibodies are produced in the laboratory and can locate and bind to cancer cells.

PN401 A substance that is being studied for its ability to protect against the gastrointestinal side effects caused by fluorouracil. It belongs to the family of drugs called cytoprotective agents. Also called triacetyluridine.

PNET Primitive neuroectodermal tumor. One of a group of cancers that develop from the same type of early cells, and share certain biochemical and genetic features. Some PNETs develop in the brain and central nervous system (CNS-PNET), and others develop in sites outside of the brain such as the limbs, pelvis and chest wall (peripheral PNET). Also called primitive neuroectodermal tumor.

pneumatic larynx A device that is used to help a person talk after a laryngectomy. It uses air to produce a humming sound, which is converted to speech by movement of the lips, tongue or glottis.

pneumonectomy An operation to remove an entire lung.

pneumonia An inflammatory infection that occurs in the lung.

PNH Paroxysmal nocturnal hemoglobinuria. A rare disorder in which red blood cells are easily destroyed by certain immune system proteins. Symptoms include blood clots, and red or brownish urine in the morning. Aplastic anemia (decreased production of blood cells) may lead to PNH, and people with PNH are at increased risk of acute myelogenous leukemia. Also called paroxysmal nocturnal hemoglobinuria.

PNU 166148 A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called topoisomerase inhibitors.

PNU-93914 A form of the anticancer drug paclitaxel that may have fewer side effects and work better than paclitaxel. It is being studied in the treatment of cancer. It belongs to the family of drugs called mitotic inhibitors. Also called LEP-ETU and paclitaxel liposome.

polifeprosan 20 carmustine implant A biodegradable wafer that is used to deliver the anticancer drug carmustine directly into a brain tumor site after the tumor has been removed by surgery. Also called Gliadel Wafer.

poly-ICLC A substance that is being studied in the treatment of cancer and for its ability to stimulate the immune system. It is made in the laboratory by combining the nucleic acid RNA with the chemicals poly-L-lysine and carboxymethyl cellulose.

polycystic ovary syndrome PCOS. A condition marked by infertility, enlarged ovaries, menstrual problems, high levels of male hormones, excess hair on the face and body, acne and obesity. Women with PCOS have an increased risk of diabetes, high blood pressure, heart disease, and endometrial cancer. Also called PCOS.

polycythemia vera A disease in which there are too many red blood cells in the bone marrow and blood, causing the blood to thicken. The number of white blood cells and platelets may also increase. The extra blood cells may collect in the spleen and cause it to become enlarged. They may also cause bleeding problems and make clots form in blood vessels.

polyethylene glycosylated recombinant human megakaryocyte growth and development factor PEG-rhMGDF. A form of megakaryocyte growth and development factor (MGDF) that is made in the laboratory. MGDF comes from the protein thrombopoietin, which is normally made in the body to help make platelets. Polyethylene glycosylated recombinant human megakaryocyte growth and development factor is being studied as a way to increase the number of platelets in patients receiving chemotherapy. Also called PEG-MGDF and PEG-rhMGDF.

polyglutamate camptothecin A form of the anticancer drug camptothecin that may have fewer side effects and work better than camptothecin. It is being studied in the treatment of cancer. It belongs to the family of drugs called DNA topoisomerase inhibitors. Also called CT-2106.

polymerase chain reaction PCR. A laboratory method used to make many copies of a specific DNA sequence. Also called PCR.

polymorphism A common variation or mutation in DNA.

polymyositis An inflammatory disease of the muscles closest to the center of the body. It causes weakness, inability to stand, climb stairs, lift or reach. It may also cause muscle pain and difficulty swallowing, and may affect the lungs and heart. Having polymyositis increases the risk of certain types of cancer.

polyneuritis Inflammation of several peripheral nerves at the same time.

polyp A growth that protrudes from a mucous membrane.

polypectomy Surgery to remove a polyp.

polyphenol A substance that is found in many plants and gives some flowers, fruits and vegetables their color. Polyphenols have antioxidant activity.

Polyphenon® E A substance that is being studied in the prevention of cancer. It is made from decaffeinated green tea, and contains chemicals called catechins, which are antioxidants. Also called green tea extract.

polyposis The development of numerous polyps (growths that protrude from a mucous membrane).

polysaccharide A type of carbohydrate. It contains sugar molecules that are linked together chemically.

polysomnogram A group of recordings taken during sleep that shows brain wave changes, eye movements, breathing rate, blood pressure, heart rate and the electrical activity of the heart and other muscles. A polysomnogram may be used to help diagnose sleep disorders.

polyvinylpyrrolidone-sodium hyaluronate gel A gel used to lessen pain from mouth sores caused by chemotherapy or radiation therapy, oral surgery, braces or disease. Polyvinylpyrrolidone-sodium hyaluronate gel is being studied in the treatment of pain caused by mouth sores in children receiving cancer treatment. It forms a thin layer over the surface of the mouth and throat to prevent irritation while eating, drinking and talking. Also called Gelclair.

pomegranate Punica granatum. A subtropical shrub or tree. Juice from the fruit may contain substances that decrease or slow the rise of prostate-specific antigen (PSA) levels. It is being studied for its ability to delay or prevent recurrent prostate cancer.

pons Part of the central nervous system, located at the base of the brain, between the medulla oblongata and the midbrain. It is part of the brainstem.

pontine Having to do with the pons (part of the central nervous system, located at the base of the brain, between the medulla oblongata and the midbrain).

porcine Having to do with or coming from pigs.

porfimer sodium A drug used to treat some types of cancer. When absorbed by cancer cells and exposed to light, porfimer sodium becomes active and kills the cancer cells. It belongs to the family of drugs called photodynamic therapy agents. Also called Photofrin.

porfiromycin A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called anticancer antibiotics.

port An implanted device through which blood may be withdrawn and drugs may be infused without repeated needle sticks. Also called a port-a-cath.

port-a-cath An implanted device through which blood may be withdrawn and drugs may be infused without repeated needle sticks. Also called a port.

portal hypertension High blood pressure in the vein that carries blood to the liver from the stomach, small and large intestines, spleen, pancreas and gallbladder. It is usually caused by a block in the blood flow through the liver due to cirrhosis (scarring) of the liver.

portal vein A blood vessel that carries blood to the liver from the stomach, small and large intestines, spleen, pancreas and gallbladder. Also called hepatic portal vein.

positive axillary lymph node A lymph node in the area of the armpit (axilla) to which cancer has spread. This spread is determined by surgically removing some of the lymph nodes and examining them under a microscope to see whether cancer cells are present.

positive test result A test result that reveals the presence of a specific disease or condition for which the test is being done.

positron emission tomography scan PET scan. A procedure in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the glucose is used. Because cancer cells often use more glucose than normal cells, the pictures can be used to find cancer cells in the body. Also called PET scan.

post-transplant lymphoproliferative disorder PTLD. A condition in which a group of B-cells grow out of control after an organ transplant in patients with weakened immune systems. This usually happens if the patient has also been infected with Epstein-Barr virus. PTLD may progress to non-Hodgkin's lymphoma. Also called PTLD.

post-traumatic stress disorder PTSD. An anxiety disorder that develops in reaction to physical injury or severe mental or emotional distress, such as military combat, violent assault, natural disaster, or other life-threatening events. Having cancer may also lead to PTSD. Symptoms interfere with day-to-day living and include reliving the event in nightmares or flashbacks; avoiding people, places, and things connected to the event; feeling alone and losing interest in daily activities; and having trouble concentrating and sleeping. Also called PTSD.

posterior In human anatomy, has to do with the back of a structure or a structure found toward the back of the body.

posterior pelvic exenteration Surgery to remove the lower part of the bowel, rectum, uterus, cervix, ovaries, fallopian tubes and vagina. Pelvic lymph nodes may also be removed.

posterior urethral cancer A disease in which malignant (cancer) cells are found in the part of the urethra (the tube through which urine leaves the body) that connects to the bladder (the organ that stores urine).

postmenopausal Having to do with the time after menopause. Menopause (“change of life”) is the time in a woman's life when menstrual periods stop permanently.

postmortem After death. Often used to describe an autopsy.

postoperative After surgery.

postprandial After a meal.

postremission therapy Anticancer drugs given to kill cancer cells that survive after remission induction therapy.

potassium A metallic element that is important in body functions such as regulation of blood pressure and of water content in cells, transmission of nerve impulses, digestion, muscle contraction and heartbeat.

potassium hydroxide A toxic and highly corrosive chemical used to make soap, in bleaching, and as a paint remover. It is used in small amounts as a food additive and in the preparation of some drugs.

potentiation In medicine, the effect of increasing the potency or effectiveness of a drug or other treatment.

power of attorney A document that gives a person (such as a relative, lawyer, or friend) the authority to make legal or financial decisions for another person. It may become active immediately, or when that person loses the ability to make decisions for himself or herself, depending on how it is written. Also called durable power of attorney and DPA.

pPNET Peripheral primitive neuroectodermal tumor. A type of cancer that forms in bone or soft tissue. Also called peripheral primitive neuroectodermal tumor and Ewing's sarcoma.

PR Progesterone receptor. A protein found inside the cells of the female reproductive tissue, some other types of tissue and some cancer cells. The hormone progesterone will bind to the receptors inside the cells and may cause the cells to grow. Also called progesterone receptor.

PR+ Progesterone receptor positive. Describes cells that have a protein to which the hormone progesterone will bind. Cancer cells that are PR+ need progesterone to grow and will usually stop growing when treated with hormones that block progesterone from binding. Also called progesterone receptor positive.

PR- Progesterone receptor negative. Describes cells that do not have a protein to which the hormone progesterone will bind. Cancer cells that are PR- do not need progesterone to grow, and usually do not stop growing when treated with hormones that block progesterone from binding. Also called progesterone receptor negative.

PR-104 A substance being studied in the treatment of cancer. PR-104 becomes active when cancer cells don’t receive enough oxygen. It may kill cancer cells by damaging their DNA.

practitioner A person who works in a specific profession. For example, a doctor or nurse is a healthcare practitioner.

Pravachol A drug that lowers the amount of cholesterol in the blood. It may also make tumor cells more sensitive to anticancer drugs, and is being studied in the treatment of cancer. It belongs to the families of drugs called HMG-CoA reductase inhibitors (statins) and chemosensitizers. Also called pravastatin.

pravastatin A drug that lowers the amount of cholesterol in the blood. It may also make tumor cells more sensitive to anticancer drugs, and is being studied in the treatment of cancer. It belongs to the families of drugs called HMG-CoA reductase inhibitors (statins) and chemosensitizers. Also called Pravachol.

precancerous A term used to describe a condition that may (or is likely to) become cancer. Also called premalignant.

precancerous dermatitis A skin disease marked by scaly or thickened patches on the skin, and often caused by prolonged exposure to arsenic. The patches often occur on sun exposed areas of the skin and in older white men. These patches may become malignant (cancerous). Also called Bowen's disease or precancerous dermatosis.

precancerous dermatosis A skin disease marked by scaly or thickened patches on the skin, and often caused by prolonged exposure to arsenic. The patches often occur on sun exposed areas of the skin and in older white men. These patches may become malignant (cancerous). Also called Bowen's disease or precancerous dermatitis.

precancerous polyps Growths that protrude from a mucous membrane. Precancerous polyps may (or are likely to) become cancer.

preclinical study Research using animals to find out if a drug, procedure or treatment is likely to be useful. Preclinical studies take place before any testing in humans is done.

precursor T-lymphoblastic leukemia A type of leukemia (blood cancer) in which too many T-cell lymphoblasts (immature white blood cells) are found in the blood and bone marrow. Also called T-cell acute lymphoblastic leukemia and T-cell acute lymphocytic leukemia.

precursor T-lymphoblastic lymphoma A type of non-Hodgkin’s lymphoma in which too many T-cell lymphoblasts (immature white blood cells) are found in the lymph nodes and spleen. It is most common in young men. Also called T-lymphoblastic lymphoma.

predictive factor A situation or condition that may increase a person's risk of developing a certain disease or disorder.

prednisolone A drug that is used to treat blood cell cancers (leukemias) and lymph system cancers (lymphomas). It belongs to the family of drugs called synthetic corticosteroids.

prednisone A drug that is used to treat several types of cancer and other disorders. Prednisone also inhibits the body's immune response. It belongs to the family of drugs called steroids.

preleukemia A group of diseases in which the bone marrow does not make enough healthy blood cells. Also called myelodysplastic syndromes and smoldering leukemia.

premalignant A term used to describe a condition that may (or is likely to) become cancer. Also called precancerous.

premature ovarian failure A condition in which the ovaries stop working before age 40. Symptoms include hot flashes, mood swings, night sweats, vaginal dryness and infertility. Some cancer treatments, such as chemotherapy, radiation therapy and surgery can cause premature ovarian failure. Ovarian failure caused by cancer treatment may be temporary or permanent and may be treated with hormone replacement therapy. Also called primary ovarian insufficiency or early menopause.

premenopausal Having to do with the time before menopause. Menopause ("change of life") is the time of life when a woman's menstrual periods stop permanently.

premycotic phase A phase of mycosis fungoides in which a patient has areas of red, scaly, itchy skin on areas of the body that are usually not exposed to sun. This is early-phase mycosis fungoides, but it is hard to diagnose the rash as mycosis fungoides during this phase. The premycotic phase may last from months to decades.

prescription A doctor's order for medicine or another intervention.

pretracheal space The area in front of the trachea (windpipe).

prevascular space The area in the front part of the chest between the lungs. Also called anterior mediastinum.

prevention In medicine, action taken to decrease the chance of getting a disease or condition. For example, cancer prevention includes avoiding risk factors (such as smoking, obesity, lack of exercise and radiation exposure) and increasing protective factors (such as getting regular physical activity, staying at a healthy weight and having a healthy diet).

preventive Used to prevent disease.

preventive mastectomy Surgery to reduce the risk of developing breast cancer by removing one or both breasts before disease develops. Also called prophylactic mastectomy.

primary care doctor A doctor who manages a person's health care over time. A primary care doctor is able to give a wide range of care, including prevention and treatment, can discuss cancer treatment choices, and can refer a patient to a specialist.

primary central nervous system lymphoma PCNSL. Cancer that forms in the lymph tissue of the brain, spinal cord, meninges (outer covering of the brain), or eye (called ocular lymphoma). Also called primary CNS lymphoma and PCNSL.

primary CNS lymphoma PCNSL. Cancer that forms in the lymph tissue of the brain, spinal cord, meninges (outer covering of the brain), or eye (called ocular lymphoma). Also called primary central nervous system lymphoma and PCNSL.

primary effusion lymphoma A rare, aggressive (fast-growing) type of B-cell non-Hodgkin’s lymphoma marked by an abnormal build-up of fluids in a body cavity. It usually occurs together with a human herpesvirus in people who have weakened immune systems, such as in AIDS.

primary endpoint The main result that is measured at the end of a study to see if a given treatment worked (e.g., the number of deaths or the difference in survival between the treatment group and the control group). What the primary endpoint will be is decided before the study begins.

primary myelofibrosis A progressive, chronic disease in which the bone marrow is replaced by fibrous tissue and blood is made in organs such as the liver and the spleen, instead of in the bone marrow. This disease is marked by an enlarged spleen and progressive anemia. Also called chronic idiopathic myelofibrosis, agnogenic myeloid metaplasia, myelosclerosis with myeloid metaplasia and idiopathic myelofibrosis.

primary ovarian insufficiency A condition in which the ovaries stop working before age 40. Symptoms include hot flashes, mood swings, night sweats, vaginal dryness and infertility. Some cancer treatments, such as chemotherapy, radiation therapy and surgery can cause primary ovarian insufficiency. Ovarian insufficiency caused by cancer treatment may be temporary or permanent and may be treated with hormone replacement therapy. Also called premature ovarian failure or early menopause.

primary tumor The original tumor.

primitive neuroectodermal tumor PNET. One of a group of cancers that develop from the same type of early cells, and share certain biochemical and genetic features. Some PNETs develop in the brain and central nervous system (CNS-PNET), and others develop in sites outside of the brain such as the limbs, pelvis and chest wall (peripheral PNET). Also called PNET.

prinomastat A substance that is being studied in the treatment of cancer. It is a matrix metalloproteinase inhibitor and belongs to the family of drugs called angiogenesis inhibitors. Also called AG3340.

pro-oxidant A substance that can produce oxygen byproducts of metabolism that can cause damage to cells.

probenecid A drug that is used to treat gout and is used together with some antibiotics to make them work better. It is being studied in the treatment of cancer. It belongs to the family of drugs called antibiotic therapy adjuncts.

procarbazine A drug that is used to treat cancer. It belongs to the family of drugs called alkylating agents.

prochlorperazine A drug used to prevent or reduce nausea and vomiting. It belongs to the family of drugs called antiemetics.

proctitis Inflammation of the mucous membrane that lines the rectum. Also called rectitis.

proctoscopy Examination of the rectum using a proctoscope, inserted into the rectum. A proctoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease.

proctosigmoidoscopy Examination of the lower colon using a sigmoidoscope, inserted into the rectum. A sigmoidoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease. Also called sigmoidoscopy.

progeny Offspring; the product of reproduction or replication.

progesterone A type of hormone made by the body that plays a role in the menstrual cycle and pregnancy. Progesterone can also be made in the laboratory. It may be used as a type of birth control and to treat menstrual disorders, infertility, symptoms of menopause and other conditions.

progesterone receptor PR. A protein found inside the cells of the female reproductive tissue, some other types of tissue, and some cancer cells. The hormone progesterone will bind to the receptors inside the cells and may cause the cells to grow. Also called PR.

progesterone receptor negative PR-. Describes cells that do not have a protein to which the hormone progesterone will bind. Cancer cells that are PR- do not need progesterone to grow, and usually do not stop growing when treated with hormones that block progesterone from binding. Also called PR-.

progesterone receptor positive PR+. Describes cells that have a protein to which the hormone progesterone will bind. Cancer cells that are PR+ need progesterone to grow and will usually stop growing when treated with hormones that block progesterone from binding. Also called PR+.

progesterone receptor test A lab test to find out if cancer cells have progesterone receptors (proteins to which the hormone progesterone will bind). If the cells have progesterone receptors, they may need progesterone to grow, and this can affect how the cancer is treated.

progestin Any natural or laboratory-made substance that has some or all of the biologic effects of progesterone, a female hormone.

prognosis The likely outcome or course of a disease; the chance of recovery or recurrence.

prognostic factor A situation or condition, or a characteristic of a patient, that can be used to estimate the chance of recovery from a disease or the chance of the disease recurring (coming back).

programmed cell death A type of cell death in which a series of molecular steps in a cell leads to its death. This is the body’s normal way of getting rid of unneeded or abnormal cells. The process of programmed cell death may be blocked in cancer cells. Also called apoptosis.

progression Increase in the size of a tumor or spread of cancer in the body.

progression-free survival One type of measurement that can be used in a clinical study or trial to help determine whether a new treatment is effective. It refers to the probability that a patient will remain alive without the disease getting worse.

progressive disease Cancer that is growing, spreading or getting worse.

proliferating Multiplying or increasing in number. In biology, cell proliferation occurs by a process known as cell division.

proliferative index A measure of the number of cells in a tumor that are dividing (proliferating). May be used with the S-phase fraction to give a more complete understanding of how fast a tumor is growing.

prolymphocytic leukemia PLL. A type of chronic lymphocytic leukemia (CLL), in which too many immature white blood cells (prolymphocytes) are found in the blood and bone marrow. PLL usually progresses more rapidly than classic CLL. Also called PLL.

promegapoietin A drug given during chemotherapy to increase blood cell regeneration. Promegapoietin is a colony-stimulating factor that stimulates the production of blood cells, especially platelets. It is a cytokine and belongs to the family of drugs called hematopoietic (blood-forming) agents.

ProMune A substance that is being studied in the treatment of some types of cancer. It belongs to the family of drugs called biological response modifiers. Also called CpG 7909 and PF-3512676.

promyelocytic leukemia An aggressive (fast-growing) type of acute myeloid leukemia in which there are too many immature blood-forming cells in the blood and bone marrow. It is usually marked by an exchange of parts of chromosomes 15 and 17. Also called acute promyelocytic leukemia and APL.

prophylactic In medicine, something that prevents or protects.

prophylactic cranial irradiation Radiation therapy to the head to reduce the risk that cancer will spread to the brain.

prophylactic mastectomy Surgery to reduce the risk of developing breast cancer by removing one or both breasts before disease develops. Also called preventive mastectomy.

prophylactic oophorectomy Surgery intended to reduce the risk of ovarian cancer by removing the ovaries before disease develops.

prophylactic surgery Surgery to remove an organ or gland that shows no signs of cancer, in an attempt to prevent development of cancer of that organ or gland. Prophylactic surgery is sometimes chosen by people who know they are at high risk for developing cancer.

prophylaxis An attempt to prevent disease.

prospective In medicine, a study or clinical trial in which participants are identified and then followed forward in time.

prospective cohort study A research study that follows over time groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke and those who do not smoke) and compares them for a particular outcome (such as lung cancer).

Prost 30 A monoclonal antibody that is being studied in the detection and treatment of cancer. Monoclonal antibodies are produced in the laboratory and can locate and bind to cancer cells.

prostate A gland in the male reproductive system. The prostate surrounds the part of the urethra (the tube that empties the bladder) just below the bladder, and produces a fluid that forms part of the semen.

prostate cancer Cancer that forms in tissues of the prostate (a gland in the male reproductive system found below the bladder and in front of the rectum). Prostate cancer usually occurs in older men.

prostate-specific antigen PSA. A substance produced by the prostate that may be found in an increased amount in the blood of men who have prostate cancer, benign prostatic hyperplasia or infection or inflammation of the prostate. Also called PSA.

prostate-specific antigen test A blood test that measures the level of prostate-specific antigen (PSA), a substance produced by the prostate and some other tissues in the body. Increased levels of PSA may be a sign of prostate cancer.

prostatectomy An operation to remove part or all of the prostate. Radical (or total) prostatectomy is the removal of the entire prostate and some of the tissue around it.

prostatic acid phosphatase PAP. An enzyme produced by the prostate. It may be found in increased amounts in men who have prostate cancer. Also called PAP.

prostatic intraepithelial neoplasia PIN. Noncancerous growth of the cells lining the internal and external surfaces of the prostate gland. Having high-grade PIN may increase the risk of developing prostate cancer. Also called PIN.

prostatitis Inflammation of the prostate gland.

prostatocystectomy Surgery to remove the bladder (the organ that holds urine), the seminal vesicles, and the prostate. The seminal vesicles and prostate are glands in the male reproductive system that help make semen. Also called cystoprostatectomy.

prosthesis A device such as an artificial leg that replaces a part of the body.

prosthodontist A dentist who specializes in replacing missing teeth or other structures of the mouth to restore an individual’s appearance, comfort or health.

prostration A condition in which a person is so tired or weak that he or she is unable to do anything.

protease inhibitor A compound that interferes with the ability of certain enzymes to break down proteins. Some protease inhibitors can keep a virus from making copies of itself (for example, AIDS virus protease inhibitors), and some can prevent cancer cells from spreading.

proteasome inhibitor A drug that blocks the action of proteasomes. A proteasome is a large protein complex that helps destroy other cellular proteins when they are no longer needed. Proteasome inhibitors are being studied in the treatment of cancer.

protective factor Something that may decrease the chance of getting a certain disease. Some examples of protective factors for cancer are getting regular physical activity, staying at a healthy weight and having a healthy diet.

protein A molecule made up of amino acids that are needed for the body to function properly. Proteins are the basis of body structures such as skin and hair and of substances such as enzymes, cytokines and antibodies.

protein kinase C PKC. An enzyme found throughout the body's tissues and organs. Several forms of PKC are involved in many cellular functions. PKC is being studied in the treatment of cancer. Also called PKC.

protein-bound paclitaxel A drug used to treat breast cancer that has spread or that has come back within 6 months after chemotherapy. It is also being studied in the treatment of newly diagnosed breast cancer and other types of cancer. Protein-bound paclitaxel belongs to the family of drugs called mitotic inhibitors. Also called nanoparticle paclitaxel, Paclitaxel (albumin-stabilized nanoparticle formulation), Abraxane and ABI-007.

proteoglycan A molecule that contains both protein and glycosaminoglycans, which are a type of polysaccharide. Proteoglycans are found in cartilage and other connective tissues.

proteomic profile An evaluation of proteins in a sample of blood. This may help detect early cancer or cancer recurrence, or help predict response to treatment.

proteomics The study of the structure and function of proteins, including the way they work and interact with each other inside cells.

protocol An action plan for a clinical trial. The plan states what the study will do, how, and why. It explains how many people will be in it, who is eligible to participate, what study agents or other interventions they will be given, what tests they will receive and how often and what information will be gathered.

proton A small, positively charged particle of matter found in the atoms of all elements. Streams of protons generated by special equipment can be used for radiation treatment.

proton beam radiation therapy A type of radiation therapy that uses protons generated by a special machine. A proton is a type of high-energy radiation that is different from an X-ray.

proton magnetic resonance spectroscopic imaging A noninvasive imaging method that provides information about cellular activity (metabolic information). It is used along with magnetic resonance imaging (MRI) which provides information about the shape and size of the tumor (spacial information). Also called magnetic resonance spectroscopic imaging and 1H-nuclear magnetic resonance spectroscopic imaging.

protozoal Having to do with the simplest organisms in the animal kingdom. Protozoa are single-cell organisms, such as amoeba, and are different from bacteria, which are not members of the animal kingdom. Some protozoa can be seen without a microscope.

proximal In medicine, refers to a part of the body that is closer to the center of the body than another part. For example, the knee is proximal to the toes. The opposite is distal.

Proxinium A substance being studied in the treatment of certain types of head and neck cancer. Proxinium is made by linking a monoclonal antibody fragment to a toxic protein that may kill cancer cells. It binds to EpCAM (a protein on the surface of epithelial cells and some types of cancer cells). Also called anti-EpCAM-Pseudomonas-exotoxin fusion protein and VB4-845.

pruritus Itching. Severe itching may be a side effect of some cancer treatments and a symptom of some types of cancers.

PS-341 A drug used to treat multiple myeloma that has gotten worse during treatment with other anticancer drugs. It is also used to treat mantle cell lymphoma in patients who have already received at least one other type of treatment. PS-341 is also being studied in the treatment of other types of cancer. It is a type of proteasome inhibitor and dipeptidyl boronic acid. Also called bortezomib and Velcade.

PSA Prostate-specific antigen. A substance produced by the prostate that may be found in an increased amount in the blood of men who have prostate cancer, benign prostatic hyperplasia or infection or inflammation of the prostate. Also called prostate-specific antigen.

psammoma body A structure found in some benign (noncancerous) or malignant (cancerous) tumor cells. Psammoma bodies look like hardened concentric rings when viewed under a microscope. They can be a sign of chronic inflammation.

PSC 833 A substance that is being studied for its ability to prevent or overcome the resistance of tumor cells to some anticancer drugs. It belongs to the family of drugs called cyclosporine analogs.

pseudomyxoma peritonei A build-up of mucus in the peritoneal cavity. The mucus may come from ruptured ovarian cysts, the appendix or from other abdominal tissues, and mucus-secreting cells may attach to the peritoneal lining and continue to secrete mucus.

psoralen A substance from plants that is sensitive to light (or can be activated by light). Psoralens are used together with UV light to treat psoriasis, vitiligo and skin nodules of cutaneous T-cell lymphoma. They are also being studied in the treatment of graft-versus-host disease. They belong to the family of drugs called furocoumarins. An example of a psoralen is methoxsalen.

psoralen and ultraviolet A therapy PUVA therapy. A type of photodynamic therapy used to treat skin conditions such as psoriasis, vitiligo, and skin nodules of cutaneous T-cell lymphoma. The patient receives psoralen (a drug that becomes active when it is exposed to light) by mouth or applied to the skin, followed by ultraviolet A radiation. PUVA therapy may increase the risk of getting skin cancer. Also called PUVA therapy.

psoriasis A chronic disease of the skin marked by red patches covered with white scales.

psychiatrist A medical doctor who specializes in the prevention, diagnosis and treatment of mental, emotional and behavioral disorders.

psychological Having to do with how the mind works and how thoughts and feelings affect behavior.

psychologist A specialist who can talk with patients and their families about emotional and personal matters, and can help them make decisions.

psychosis A severe mental disorder in which a person loses the ability to recognize reality or relate to others. The person is not able to cope with the demands of everyday life. Symptoms include being paranoid, having false ideas about what is taking place or who one is, and seeing, hearing or feeling things that are not there.

psychostimulant A drug that causes a sense of well-being, decreases fatigue and depression and increases the desire to eat. These drugs can also cause mood changes and trouble with sleeping.

psychotherapy Treatment of mental, emotional, personality and behavioral disorders using methods such as discussion, listening and counseling. Also called talk therapy.

PT-100 A substance being studied in the treatment of cancer, including certain types of lung, pancreas and brain cancer. PT-100 may help the immune system block the growth of cancer cells. It may also increase the growth of new blood cells. It is a type of enzyme inhibitor. Also called talabostat and talabostat mesylate.

PTC Percutaneous transhepatic cholangiography (per-kyoo-TAN-ee-us trans-heh-PAT-ik ko-LAN-jee-AH-gra-fee). A procedure to X-ray the hepatic and common bile ducts. A contrasting agent is injected into the liver or bile duct, and the ducts are then X-rayed to find the point of obstruction. Also called percutaneous transhepatic cholangiography.

PTCD Percutaneous transhepatic cholangiodrainage. A procedure to drain bile to relieve pressure in the bile ducts caused by a blockage. An X-ray of the liver and bile ducts locates the blockage of bile flow. Images made by ultrasound guide placement of a stent (tube), which remains in the liver. Bile drains through the stent into the small intestine or into a collection bag outside the body. This procedure may relieve jaundice before surgery. Also called percutaneous transhepatic biliary drainage and percutaneous transhepatic cholangiodrainage.

PTH A substance made by the parathyroid gland that helps the body store and use calcium. A higher-than-normal amount of PTH causes high levels of calcium in the blood and may be a sign of disease. Also called parathormone, parathyrin and parathyroid hormone.

PTK787/ZK 222584 A substance that is being studied in the treatment of cancer. It belongs to the families of drugs called protein tyrosine kinase inhibitors and VEGF receptor kinase inhibitors. Also called vatalanib.

PTLD Post-transplant lymphoproliferative disorder. A condition in which a group of B-cells grow out of control after an organ transplant in patients with weakened immune systems. This usually happens if the patient has also been infected with Epstein-Barr virus. PTLD may progress to non-Hodgkin's lymphoma. Also called post-transplant lymphoproliferative disorder.

ptosis Drooping of the upper eyelid.

PTSD Post-traumatic stress disorder. An anxiety disorder that develops in reaction to physical injury or severe mental or emotional distress, such as military combat, violent assault, natural disaster, or other life-threatening events. Having cancer may also lead to PTSD. Symptoms interfere with day-to-day living and include reliving the event in nightmares or flashbacks; avoiding people, places, and things connected to the event; feeling alone and losing interest in daily activities; and having trouble concentrating and sleeping. Also called post-traumatic stress disorder.

puberty The time of life when a child experiences physical and hormonal changes that mark a transition into adulthood. The child develops secondary sexual characteristics and becomes able to have children. Secondary sexual characteristics include growth of pubic, armpit, and leg hair; breast enlargement; and increased hip width in girls. In boys, they include growth of pubic, face, chest and armpit hair; voice changes; penis and testicle growth and increased shoulder width.

pulmonary Having to do with the lungs.

pulmonary rehabilitation education Education about behavior and lifestyle changes to help patients with chronic lung disease decrease breathing problems, return to daily activities, and improve quality of life. Education may include instruction about breathing exercises, nutrition, use of medicines and ways for the patient to reduce stress and save energy.

pulmonary sulcus tumor A type of lung cancer that begins in the upper part of a lung and spreads to nearby tissues such as the ribs and vertebrae. Most pulmonary sulcus tumors are non-small cell cancers. Also called Pancoast tumor.

pulmonologist A doctor who specializes in treating diseases of the lungs.

pump A device that is used to give a controlled amount of a liquid at a specific rate. For example, pumps are used to give drugs (such as chemotherapy or pain medicine) or nutrients.

punch biopsy Removal of a small disk-shaped sample of tissue using a sharp, hollow device. The tissue is then examined under a microscope.

Purinethol A drug used to treat acute lymphatic leukemia. It belongs to the family of drugs called antimetabolites. Also called mercaptopurine.

purple clover Trifolium pratense. A plant with flowers that has been used in some cultures to treat certain medical problems. It is being studied in the relief of menopausal symptoms and may have anticancer effects. Also called red clover, wild clover and Trifolium pratense.

purple coneflower An herb native to North America that has been used to prevent and treat the common cold and other respiratory infections. Purple coneflower may interfere with treatment that uses the immune system to fight cancer. The scientific names are Echinacea purpurea and Echinacea angustifolia. Also called echinacea.

PUVA therapy Psoralen and ultraviolet A therapy. A type of photodynamic therapy used to treat skin conditions such as psoriasis, vitiligo, and skin nodules of cutaneous T-cell lymphoma. The patient receives psoralen (a drug that becomes active when it is exposed to light) by mouth or applied to the skin, followed by ultraviolet A radiation. PUVA therapy may increase the risk of getting skin cancer. Also called psoralen and ultraviolet A therapy.

PV701 A virus that is being studied in the treatment of cancer. It belongs to the family of viruses that cause Newcastle disease in birds.

PXD101 A substance being studied in the treatment of certain blood diseases, blood cancers, and other types of cancer. PXD101 may block the growth of tumors and the growth of blood vessels from surrounding tissue to the tumor. It may also make tumor cells more sensitive to other anticancer drugs. PXD101 is a type of histone deacetylase (HDAC) inhibitor and angiogenesis inhibitor.

pyrazine diazohydroxide A substance that is being studied in the treatment of cancer.

pyrazoloacridine A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called acridines.

pyridoxine A key nutrient that the body needs to break down proteins, carbohydrates, and fats in food for healthy blood, skin, and nerves. It is found in many foods, including meats, bananas, legumes, eggs and whole grains. Pyridoxine is being studied in the prevention of hand-foot syndrome (a disorder sometimes caused by certain anticancer drugs). Hand-foot syndrome is marked by pain, swelling, numbness, tingling or redness of the hands or feet. Also called vitamin B6.

pyroxamide A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called histone deacetylase inhibitors.

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