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Glossary of Cancer Terms

E

E7070 A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called sulfonamides.

E7389 A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called antitubulin agents.

early menopause 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 early menopause. Early menopause caused by cancer treatment may be temporary or permanent and may be treated with hormone replacement therapy. Also called premature ovarian failure or primary ovarian insufficiency.

early-stage breast cancer Breast cancer that has not spread beyond the breast or the axillary lymph nodes. This includes ductal carcinoma in situ and stage I, stage IIA, stage IIB and stage IIIA breast cancers.

Eastern red cedar A type of evergreen tree with hard fragrant wood that is a member of the cypress family. The oil from the wood is used in soaps, shampoos, bath salts, perfumes, aromatherapy and to keep insects away. The scientific name is Juniperus virginiana. Also called cedarwood and red cedar.

EBV Epstein-Barr virus. A common virus that remains dormant in most people. It has been associated with certain cancers, including Burkitt's lymphoma, immunoblastic lymphoma and nasopharyngeal carcinoma.

ecchymosis A small bruise caused by blood leaking from broken blood vessels into the tissues of the skin or mucous membranes.

eccrine gland A type of simple sweat gland that is found in almost all regions of the skin. These glands produce sweat that reaches the surface of the skin by way of coiled ducts (tubes). The body is cooled as sweat evaporates from the skin.

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

echocardiography A procedure that uses ultrasonic waves directed over the chest wall to obtain a graphic record of the heart's position, motion of the walls or internal parts such as the valves.

ECT Electroconvulsive therapy. A treatment for severe depression and certain mental disorders. A brief seizure is induced by giving electrical stimulation to the brain through electrodes placed on the scalp. Also called electroconvulsive therapy and electroshock therapy.

ecteinascidin 743 An anticancer drug that inhibits the growth of cancer cells by disrupting the structure of tumor-cell DNA.

ectocervical Having to do with the part of the cervix that protrudes into the vagina and is lined with epithelial cells.

ectomesenchymoma A rare, fast-growing tumor of the nervous system or soft tissue that occurs in children and young adults. Ectomesenchymomas may form in the head and neck, abdomen, perineum, scrotum or limbs. Also called malignant ectomesenchymoma.

eculizumab A monoclonal antibody that is being studied in the prevention of red blood cell destruction in patients with paroxysmal nocturnal hemoglobinuria (a red blood cell disorder).

eczema A group of conditions in which the skin becomes inflamed, forms blisters, and becomes crusty, thick, and scaly. Eczema causes burning and itching, and may occur over a long period of time. Atopic dermatitis is the most common type of eczema.

edatrexate An anticancer drug that belongs to a family of drugs called antimetabolites.

edema Swelling caused by excess fluid in body tissues.

edotecarin A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called topoisomerase I inhibitors. Also called J-107088.

edrecolomab A type of monoclonal antibody used in cancer detection or therapy. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells.

EEG Electroencephalogram. A recording of electrical activity in the brain. It is made by placing electrodes on the scalp (the skin covering the top of the head), and impulses are sent to a special machine. An EEG may be used to diagnose brain and sleep disorders. Also called electroencephalogram.

EF5 A drug that is used to plan cancer treatment by measuring oxygen levels in tumor cells.

efaproxiral A drug that may increase the effectiveness of radiation therapy. Also called RSR13.

effector cell A cell that performs a specific function in response to a stimulus; usually used to describe cells in the immune system.

efficacy Effectiveness. In medicine, the ability of an intervention (for example, a drug or surgery) to produce the desired beneficial effect.

effusion An abnormal collection of fluid in hollow spaces or between tissues of the body. For example, a pleural effusion is a collection of fluid between the two layers of membrane covering the lungs.

eflornithine A substance that is being studied in the prevention of cancer. It belongs to the family of drugs called antiprotozoals.

EGb761 A substance that is being studied in the prevention of cognitive dysfunction (slowed ability to think, reason, concentrate or remember) in patients receiving chemotherapy. It comes from ginkgo biloba leaves.

EGFR Epidermal growth factor receptor. The protein found on the surface of some cells and to which epidermal growth factor binds, causing the cells to divide. It is found at abnormally high levels on the surface of many types of cancer cells, so these cells may divide excessively in the presence of epidermal growth factor. Also called epidermal growth factor receptor, ErbB1 and HER1.

ejaculation The release of semen through the penis during orgasm.

EKB-569 A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called epidermal growth factor receptor inhibitors.

electroacupuncture A procedure in which pulses of weak electrical current are sent through acupuncture needles into acupuncture points in the skin. This procedure is being studied in the prevention of nausea and vomiting in patients undergoing chemotherapy.

electroconvulsive therapy ECT. A treatment for severe depression and certain mental disorders. A brief seizure is induced by giving electrical stimulation to the brain through electrodes placed on the scalp. Also called ECT and electroshock therapy.

electrodermal response A change in the way electricity moves through the skin, often caused by stress or anxiety.

electrodesiccation The drying of tissue by a high-frequency electric current applied with a needle-shaped electrode.

electrodiathermy A procedure in which tissue is heated to destroy abnormal cells. The heat may come from electric currents, microwaves, radio waves or ultrasound. Electrodiathermy is a type of hyperthermia therapy. Also called diathermy.

electroencephalogram EEG. A recording of electrical activity in the brain. It is made by placing electrodes on the scalp (the skin covering the top of the head), and impulses are sent to a special machine. An EEG may be used to diagnose brain and sleep disorders.

electrofulguration A procedure to destroy tissue (such as a tumor) using an electric current. Also called fulguration.

electrolarynx A battery-operated device that makes a humming sound. It is used to help a person talk after removal of the larynx (voice box).

electrolyte A substance that breaks up into ions (electrically charged particles) when it is dissolved in body fluids or water. Some examples of electrolytes are sodium, potassium, chloride, and calcium. Electrolytes are primarily responsible for the movement of nutrients into cells and the movement of wastes out of cells.

electromagnetic field Low-energy radiation that comes from the interaction of electric and magnetic fields. Sources include power lines, electric appliances, radio waves, microwaves and others. Also called electromagnetic radiation.

electromagnetic radiation Low-energy radiation that comes from the interaction of electric and magnetic fields. Sources include power lines, electric appliances, radio waves, microwaves and others. Also called electromagnetic field.

electron beam A stream of electrons (small negatively charged particles found in atoms) that can be used for radiation therapy.

electron microscope A microscope (device used to magnify small objects) that uses electrons (instead of light) to produce an enlarged image. An electron microscope shows tiny details better than any other type of microscope.

electroporation therapy EPT. Treatment that generates electrical pulses through an electrode placed in a tumor to enhance the ability of anticancer drugs to enter tumor cells.

electroshock therapy A treatment for severe depression and certain mental disorders. A brief seizure is induced by giving electrical stimulation to the brain through electrodes placed on the scalp. Also called electroconvulsive therapy and ECT.

eligibility criteria In clinical trials, requirements that must be met for an individual to be included in a study. These requirements help make sure that patients in a trial are similar to each other in terms of specific factors such as age, type and stage of cancer, general health and previous treatment. When all participants meet the same eligibility criteria, it gives researchers greater confidence that results of the study are caused by the intervention being tested and not by other factors.

Ellence A drug used together with other drugs to treat early breast cancer that has spread to lymph nodes. It is also being studied in the treatment of other types of cancer. Ellence is a type of anthracycline antibiotic. Also called epirubicin and epirubicin hydrochloride.

Eloxatin A drug used to treat colorectal cancer that is advanced or has come back. It is also being studied in the treatment of other types of cancer. Eloxatin belongs to the family of drugs called platinum compounds. Also called oxaliplatin.

embolism A block in an artery caused by blood clots or other substances, such as fat globules, infected tissue or cancer cells.

embolization The blocking of an artery by a clot or foreign material. Embolization can be done as treatment to block the flow of blood to a tumor.

embryo Early stage in the development of a plant or an animal. In vertebrate animals (have a backbone or spinal column), this stage lasts from shortly after fertilization until all major body parts appear. In particular, in humans, this stage lasts from about 2 weeks after fertilization until the end of the seventh or eighth week of pregnancy.

embryoma A mass of rapidly growing cells that begins in embryonic (fetal) tissue. Embryomas may be benign or malignant, and include neuroblastomas and Wilms’ tumors. Also called embryonal tumor.

embryonal rhabdomyosarcoma A soft-tissue tumor that affects children. It begins in muscle cells, and usually occurs in the head, neck, arms, legs or genitourinary tract.

embryonal tumor A mass of rapidly growing cells that begins in embryonic (fetal) tissue. Embryonal tumors may be benign or malignant, and include neuroblastomas and Wilms’ tumors. Also called embryoma.

embryonic Having to do with an embryo, which is an early stage in the development of a plant or animal.

EMD 121974 A substance that is being studied as an anticancer and antiangiogenesis drug. Also called cilengitide.

EMD 72000 A monoclonal antibody that is being studied in the treatment of some types of cancer. Monoclonal antibodies are made in the laboratory and can locate and bind to cancer cells. EMD 72000 binds to the epithelial growth factor receptor (EGFR) on tumor cells and blocks growth signals. Also called matuzumab.

Emend A drug used to prevent and control the nausea and vomiting caused by chemotherapy. It is used together with other anti-vomiting medicines. It belongs to the family of drugs called antiemetic agents. Also called aprepitant.

emesis Vomiting.

emetic Describes a substance that causes vomiting. Also called emetogenic.

emetogenic Describes a substance that causes vomiting. Also called emetic.

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

emodin A substance found in certain plants, including rhubarb. It belongs to a family of compounds called anthraquinones, which have shown anti-inflammatory and anticancer effects.

emphysema Pulmonary emphysema is a disorder affecting the alveoli (tiny air sacs) of the lungs. The transfer of oxygen and carbon dioxide in the lungs takes place in the walls of the alveoli. In emphysema, the alveoli become abnormally inflated, damaging their walls and making it harder to breathe. People who smoke or have chronic bronchitis have an increased risk of emphysema.

enalapril An antihypertensive agent that can also be used to slow or prevent the progression of heart disease in people with childhood cancer treated with drugs that may be harmful to the heart.

encapsulated Confined to a specific, localized area and surrounded by a thin layer of tissue.

encephalopathy A disorder of the brain that can be caused by disease, injury, drugs or chemicals.

enchondroma A benign (noncancerous) growth of cartilage in bones or in other areas where cartilage is not normally found.

endocarditis A condition in which the tissues lining the inside of the heart and the heart valves become inflamed (red and swollen). Endocarditis may be caused by infection with microorganisms, such as bacteria or fungi.

endocervical curettage A procedure in which the mucous membrane of the cervical canal is scraped using a spoon-shaped instrument called a curette.

endocrine Refers to tissue that makes and releases hormones that travel in the bloodstream and control the actions of other cells or organs. Some examples of endocrine tissues are the pituitary, thyroid and adrenal glands.

endocrine cancer Cancer that occurs in endocrine tissue, the tissue in the body that secretes hormones.

endocrine pancreas cell A pancreatic cell that produces hormones (e.g., insulin and glucagon) that are secreted into the bloodstream. These hormones help control the level of glucose (sugar) in the blood. Also called islet cell and islet of Langerhans cell.

endocrine system A system of glands and cells that make hormones that are released directly into the blood and travel to tissues and organs all over the body. The endocrine system controls growth, sexual development, sleep, hunger and the way the body uses food.

endocrine therapy Treatment that adds, blocks or removes hormones. For certain conditions (such as diabetes or menopause), hormones are given to adjust low hormone levels. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body’s natural hormones. Sometimes surgery is needed to remove the gland that makes a certain hormone. Also called hormone therapy, hormonal therapy or hormone treatment.

endocrinologist A doctor who specializes in diagnosing and treating hormone disorders.

endogenous Produced inside an organism or cell. The opposite is external (exogenous) production.

endometrial Having to do with the endometrium (the layer of tissue that lines the uterus).

endometrial biopsy A procedure in which a sample of tissue is taken from the endometrium (inner lining of the uterus) for examination under a microscope. A thin tube is inserted through the cervix into the uterus, and gentle scraping and suction are used to remove the sample.

endometrial cancer Cancer that forms in the tissue lining the uterus (the small, hollow, pear-shaped organ in a woman's pelvis in which a baby grows). Most endometrial cancers are adenocarcinomas (cancers that begin in cells that make and release mucus and other fluids).

endometrial disorder Abnormal cell growth in the endometrium (the lining of the uterus).

endometrial hyperplasia An abnormal overgrowth of the endometrium (the layer of cells that lines the uterus). There are four types of endometrial hyperplasia: simple endometrial hyperplasia, complex endometrial hyperplasia, simple endometrial hyperplasia with atypia and complex endometrial hyperplasia with atypia. These differ in terms of how abnormal the cells are and how likely it is that the condition will become cancerous.

endometriosis A benign condition in which tissue that looks like endometrial tissue grows in abnormal places in the abdomen.

endometrium The layer of tissue that lines the uterus.

endorectal ultrasound ERUS. A procedure in which a probe that sends out high-energy sound waves is inserted into the rectum. The sound waves are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissue called a sonogram. ERUS is used to look for abnormalities in the rectum and nearby structures, including the prostate. Also called ERUS, transrectal ultrasound and TRUS.

endorphin A morphine-like chemical that is made naturally in the brain and relieves pain.

endoscope A thin, tube-like instrument used to look at tissues inside the body. An endoscope has a light and a lens for viewing and may have a tool to remove tissue.

endoscopic retrograde cholangiopancreatography ERCP. A procedure that uses an endoscope to examine and X-ray the pancreatic duct, hepatic duct, common bile duct, duodenal papilla and gallbladder. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. The endoscope is passed through the mouth and down into the first part of the small intestine (duodenum). A smaller tube (catheter) is then inserted through the endoscope into the bile and pancreatic ducts. A dye is injected through the catheter into the ducts, and an X-ray is taken. Also called ERCP.

endoscopic ultrasound EUS. A procedure in which an endoscope is inserted into the body. An endoscope is a thin, tube-like instrument that has a light and a lens for viewing. A probe at the end of the endoscope is used to bounce high-energy sound waves (ultrasound) off internal organs to make a picture (sonogram). Also called EUS and endosonography.

endoscopy A procedure that uses an endoscope to examine the inside of the body. An endoscope 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.

endosonography A procedure in which an endoscope is inserted into the body. An endoscope is a thin, tube-like instrument that has a light and a lens for viewing. A probe at the end of the endoscope is used to bounce high-energy sound waves (ultrasound) off internal organs to make a picture (sonogram). Also called endoscopic ultrasound and EUS.

endostatin A drug that is being studied for its ability to prevent the growth of new blood vessels into a solid tumor. Endostatin belongs to the family of drugs called angiogenesis inhibitors.

endothelial cell The main type of cell found in the inside lining of blood vessels, lymph vessels and the heart.

endothelin receptor antagonist A drug that blocks the hormone endothelin and may prevent prostate cancer from spreading to the bones. It may also prevent the growth and spread of other types of cancer, including colorectal cancer.

endothelin-1 protein receptor antagonist A substance that blocks the binding of the endothelin-1 protein to its receptor. Endothelin-1 is a small molecule that causes changes in blood vessels and helps regulate blood pressure. It can also stimulate the growth of some types of cells.

endpoint In clinical trials, an event or outcome that can be measured objectively to determine whether the intervention being studied is beneficial. The endpoints of a clinical trial are usually included in the study objectives. Some examples of endpoints are survival, improvements in quality of life, relief of symptoms and disappearance of the tumor.

enema The injection of a liquid through the anus into the large bowel.

energy balance In biology, the state at which the number of calories eaten equals the number of calories used. Energy balance is affected by physical activity, body size, amount of body fat and muscle and genetics.

English lavender A plant with aromatic leaves and flowers that is a member of the mint family. Oil from the flowers has been used in some cultures to treat certain medical problems, to keep insects away, and to wash in. It is also used in aromatherapy. Perillyl alcohol, a substance found in English lavender, is being studied in cancer prevention and treatment. The scientific name is Lavandula angustifolia. Also called lavender and true lavender.

eniluracil An anticancer drug that increases the effectiveness of fluorouracil. Also called ethynyluracil.

enoxaparin A drug used to prevent blood clots. It belongs to the family of drugs called anticoagulants.

ENT doctor A doctor who specializes in treating diseases of the ear, nose and throat. Also called otolaryngologist.

Entelev A liquid that has been promoted as a treatment for a wide range of diseases, including cancer. The ingredients thought to be in Entelev have been tested, and none of them has been shown to be effective in treating any form of cancer. Entelev is not available in the United States. Also called Cancell, Sheridan’s Formula, Jim’s Juice, Crocinic Acid, JS–114, JS–101, 126–F and Cantron.

enteral nutrition A form of nutrition that is delivered into the digestive system as a liquid. Drinking nutrition beverages or formulas and tubefeeding are forms of enteral nutrition. People who are unable to meet their needs with food and beverages alone, and who do not have vomiting or uncontrollable diarrhea may be given tubefeedings. Tubefeeding can be used to add to what a person is able to eat or can be the only source of nutrition. A small feeding tube may be placed through the nose into the stomach or the small intestine, or it may be surgically placed into the stomach or the intestinal tract through an opening made on the outside of the abdomen, depending on how long it will be used.

enterostomal therapist A health professional trained in the care of persons with stomas, such as colostomies or urostomies.

enucleation In medicine, the removal of an organ or tumor in such a way that it comes out clean and whole, like a nut from its shell.

enveloped virus A virus that has an outer wrapping or envelope. This envelope comes from the infected cell, or host, in a process called "budding off." During the budding process, newly formed virus particles become "enveloped" or wrapped in an outer coat that is made from a small piece of the cell's plasma membrane. The envelope may play a role in helping a virus survive and infect other cells.

environmental tobacco smoke ETS. Smoke that comes from the burning of a tobacco product and smoke that is exhaled by smokers (second-hand smoke). Inhaling ETS is called involuntary or passive smoking.

enzastaurin A drug used to treat brain tumors. It is being studied in the treatment of advanced colorectal cancer. It belongs to the families of drugs called protein kinase inhibitors and angiogenesis inhibitors. Also called enzastaurin hydrochloride and LY317615.

enzastaurin hydrochloride A drug used to treat brain tumors. It is being studied in the treatment of advanced colorectal cancer. It belongs to the families of drugs called protein kinase inhibitors and angiogenesis inhibitors. Also called enzastaurin and LY317615.

enzyme A protein that speeds up chemical reactions in the body.

eosinophil A type of white blood cell.

eosinophilia A condition in which the number of eosinophils (a type of white blood cell) in the blood is greatly increased. Eosinophilia is often a response to infection or allergens (substances that cause an allergic response).

EP-2101 A substance that is being studied as a treatment for cancer. It belongs to the family of drugs called cancer vaccines.

ependymal tumor A brain tumor that usually begins in the central canal of the spinal cord. Ependymal tumors may also develop in the cells lining the ventricles of the brain, which produce and store the special fluid (cerebrospinal fluid) that protects the brain and spinal cord. Also called an ependymoma.

ependymoma A type of brain tumor that may arise in the ventricles of the brain or in the spinal cord. Also called an ependymal tumor.

ephedra Ephedra sinica. A shrub native to China and India. The stems and roots are used in traditional medicine as a diuretic and for asthma, bronchitis and cough. It has also been promoted as a decongestant, a weight loss aid and as a supplement to increase energy. Ephedra may cause high blood pressure, increased heart rate or death if used with certain drugs, and may reduce the effects of certain drugs used to treat cancer and other diseases. The U.S. Food and Drug Administration has banned the sale of dietary supplements that contain ephedra. Also called ma huang.

epidemiologist A scientist who studies the patterns, causes and control of disease in groups of people.

epidemiology The study of the patterns, causes and control of disease in groups of people.

epidermal growth factor receptor EGFR. The protein found on the surface of some cells and to which epidermal growth factor binds, causing the cells to divide. It is found at abnormally high levels on the surface of many types of cancer cells, so these cells may divide excessively in the presence of epidermal growth factor. Also called EGFR, ErbB1 and HER1.

epidermis The upper or outer layer of the two main layers of tissue that make up the skin.

epidermoid carcinoma Cancer that begins in squamous cells, which are thin, flat cells that look like fish scales. Squamous cells are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the lining of the respiratory and digestive tracts. Also called squamous cell carcinoma.

epidural Having to do with the space between the wall of the spinal canal and the covering of the spinal cord. An epidural injection is given into this space.

epidural block An injection of an anesthetic drug into the space between the wall of the spinal canal and the covering of the spinal cord.

epigastric Having to do with the upper middle area of the abdomen.

epiglottis The flap that covers the trachea during swallowing so that food does not enter the lungs.

epilepsy A group of disorders marked by problems in the normal functioning of the brain. These problems can produce seizures, unusual body movements, a loss of consciousness or changes in consciousness, as well as mental problems or problems with the senses.

epinephrine A hormone and neurotransmitter. Also called adrenaline.

epipodophyllotoxin A substance that is being studied in the treatment of some types of cancer. Epipodophyllotoxin is extracted from the mandrake root Podophyllum peltatum. It belongs to the family of drugs called topoisomerase inhibitors.

epirubicin A drug used together with other drugs to treat early breast cancer that has spread to lymph nodes. It is also being studied in the treatment of other types of cancer. Epirubicin is a type of anthracycline antibiotic. Also called epirubicin hydrochloride and Ellence.

epirubicin hydrochloride A drug used together with other drugs to treat early breast cancer that has spread to lymph nodes. It is also being studied in the treatment of other types of cancer. Epirubicin hydrochloride is a type of anthracycline antibiotic. Also called epirubicin and Ellence.

epithelial Refers to the cells that line the internal and external surfaces of the body.

epithelial carcinoma Cancer that begins in the cells that line an organ.

epithelial ovarian cancer Cancer that occurs in the cells on the surface of the ovary. Also called ovarian epithelial cancer.

epithelium A thin layer of tissue that covers organs, glands and other structures within the body.

epitope A part of a molecule that an antibody will recognize and bind to.

EPO906 A substance that is being studied as a treatment for cancer. It belongs to the family of drugs called epothilones. Also called epothilone B.

epoetin alfa A substance that is made in the laboratory and stimulates the bone marrow to make red blood cells. It belongs to the family of drugs called antianemics. Epoetin alfa is a type of recombinant human erythropoietin.

epoetin beta A substance that is made in the laboratory and stimulates the bone marrow to make red blood cells. It belongs to the family of drugs called antianemics. Epoetin beta is a type of recombinant human erythropoietin.

epothilone A substance obtained from bacteria that interferes with cell division. Some epothilones are being studied as treatments for cancer.

epothilone B A substance being studied as a treatment for cancer. It is a type of epothilone. Also called EPO906.

epothilone D A substance being studied in the treatment of cancer. It is a type of mitotic inhibitor and epothilone. Also called KOS-862.

epratuzumab A substance that is being studied as a treatment for cancer. It belongs to the family of drugs called radiolabeled monoclonal antibodies.

Epstein-Barr virus EBV. A common virus that remains dormant in most people. It has been associated with certain cancers, including Burkitt's lymphoma, immunoblastic lymphoma and nasopharyngeal carcinoma.

EPT Electroporation therapy. Treatment that generates electrical pulses through an electrode placed in a tumor to enhance the ability of anticancer drugs to enter tumor cells.

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

ER+ Estrogen receptor positive. Describes cells that have a protein to which the hormone estrogen will bind. Cancer cells that are ER+ need estrogen to grow, and may stop growing when treated with hormones that block estrogen from binding.

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

ERA-923 A substance that is being studied as a treatment for cancer. It belongs to a family of drugs called antiestrogens.

erb-38 immunotoxin A toxic substance linked to an antibody that attaches to tumor cells and kills them.

ErbB1 Epidermal growth factor receptor. The protein found on the surface of some cells and to which epidermal growth factor binds, causing the cells to divide. It is found at abnormally high levels on the surface of many types of cancer cells, so these cells may divide excessively in the presence of epidermal growth factor. Also called epidermal growth factor receptor, EGFR and HER1.

Erbitux A monoclonal antibody used to treat certain types of head and neck cancer, and colorectal cancer that has spread to other parts of the body. 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. Erbitux binds to the epidermal growth factor receptor (EGFR), which is found on the surface of some types of cancer cells. Also called cetuximab.

ERCP Endoscopic retrograde cholangiopancreatography. A procedure that uses an endoscope to examine and X-ray the pancreatic duct, hepatic duct, common bile duct, duodenal papilla and gallbladder. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. The endoscope is passed through the mouth and down into the first part of the small intestine (duodenum). A smaller tube (catheter) is then inserted through the endoscope into the bile and pancreatic ducts. A dye is injected through the catheter into the ducts, and an X-ray is taken. Also called endoscopic retrograde cholangiopancreatography.

erectile dysfunction An inability to have an erection of the penis adequate for sexual intercourse. Also called impotence.

erection In medicine, the swelling of the penis with blood, causing it to become firm.

erlotinib A drug used to treat certain types of non-small cell lung cancer. It is also used together with gemcitabine to treat pancreatic cancer and is being studied in the treatment of other types of cancer. Erlotinib belongs to the family of drugs called epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors. Also called erlotinib hydrochloride, CP-358,774, OSI-774 and Tarceva.

erlotinib hydrochloride A drug used to treat certain types of non-small cell lung cancer. It is also used together with gemcitabine to treat pancreatic cancer and is being studied in the treatment of other types of cancer. Erlotinib hydrochloride belongs to the family of drugs called epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors. Also called erlotinib, CP-358,774, OSI-774 and Tarceva.

ERT Estrogen replacement therapy. Hormones (estrogen, progesterone or both) given to postmenopausal women or to women who have had their ovaries surgically removed. Hormones are given to replace the estrogen no longer produced by the ovaries.

ERUS Endorectal ultrasound. A procedure in which a probe that sends out high-energy sound waves is inserted into the rectum. The sound waves are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissue called a sonogram. ERUS is used to look for abnormalities in the rectum and nearby structures, including the prostate. Also called endorectal ultrasound, transrectal ultrasound and TRUS.

erythema Redness of the skin.

erythrocyte A cell that carries oxygen to all parts of the body. Also called red blood cell and RBC.

erythrocyte sedimentation rate ESR. The distance red blood cells travel in one hour in a sample of blood as they settle to the bottom of a test tube. The sedimentation rate is increased in inflammation, infection, cancer, rheumatic diseases and diseases of the blood and bone marrow. Also called ESR and sedimentation rate.

erythrodysplasia A condition in which immature red blood cells (erythroid cells) in the bone marrow are abnormal in size, shape, organization and/or number. Erythrodysplasia may be caused by vitamin deficiency or chemotherapy, or it may be a sign of refractory anemia, which is a myelodysplastic syndrome. Also called erythroid dysplasia.

erythroid dysplasia A condition in which immature red blood cells (erythroid cells) in the bone marrow are abnormal in size, shape, organization and/or number. Erythroid dysplasia may be caused by vitamin deficiency or chemotherapy, or it may be a sign of refractory anemia, which is a myelodysplastic syndrome. Also called erythrodysplasia.

erythroleukemia Cancer of the blood-forming tissues in which large numbers of immature, abnormal red blood cells are found in the blood and bone marrow.

erythroleukoplakia An abnormal patch of red and white tissue that forms on mucous membranes in the mouth and may become cancerous. Tobacco (smoking or chewing) and alcohol may increase the risk of erythroleukoplakia.

erythroplakia An abnormal patch of red tissue that forms on mucous membranes in the mouth and may become cancerous. Tobacco (smoking and chewing) and alcohol may increase the risk of erythroplakia.

erythropoietin A substance that is naturally produced by the kidneys, and that stimulates the bone marrow to make red blood cells. When erythropoietin is made in the laboratory, it is called epoetin alfa or epoetin beta.

escitalopram A drug used to treat depression and certain anxiety disorders. It belongs to the family of drugs called selective serotonin reuptake inhibitors (SSRIs). Also called Lexapro.

esomeprazole A drug that blocks acid from being made in the stomach. It is used to treat acid reflux disease and to prevent certain types of gastrointestinal ulcers. Esomeprazole is being studied in the prevention of esophageal cancer and in the treatment of other conditions, including side effects of chemotherapy. It is a type of anti-ulcer agent. Also called esomeprazole magnesium and Nexium.

esomeprazole magnesium A drug that blocks acid from being made in the stomach. It is used to treat acid reflux disease and to prevent certain types of gastrointestinal ulcers. Esomeprazole magnesium is being studied in the prevention of esophageal cancer and in the treatment of other conditions, including side effects of chemotherapy. It is a type of anti-ulcer agent. Also called esomeprazole and Nexium.

esophageal Having to do with the esophagus, the muscular tube through which food passes from the throat to the stomach.

esophageal cancer Cancer that forms in tissues lining the esophagus (the muscular tube through which food passes from the throat to the stomach). Two types of esophageal cancer are squamous cell carcinoma (cancer that begins in flat cells lining the esophagus) and adenocarcinoma (cancer that begins in cells that make and release mucus and other fluids).

esophageal reflux The backward flow of stomach acid contents into the esophagus (the tube that connects the mouth to the stomach). Also called gastroesophageal reflux or gastric reflux.

esophageal speech Speech produced by trapping air in the esophagus and forcing it out again. It is used after removal of a person's larynx (voice box).

esophageal stent A tube placed in the esophagus to keep a blocked area open so the patient can swallow soft food and liquids. Esophageal stents are made of metal mesh, plastic or silicone, and may be used in the treatment of esophageal cancer.

esophagectomy An operation to remove a portion of the esophagus.

esophagitis Inflammation of the esophagus (the tube that carries food from the mouth to the stomach).

esophagoscopy Examination of the esophagus using an esophagoscope. An esophagoscope 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.

esophagram A series of X-rays of the esophagus. The X-ray pictures are taken after the person drinks a solution that contains barium. The barium coats and outlines the esophagus on the X-ray. Also called barium swallow and upper GI series.

esophagus The muscular tube through which food passes from the throat to the stomach.

ESR Erythrocyte sedimentation rate. The distance red blood cells travel in one hour in a sample of blood as they settle to the bottom of a test tube. The sedimentation rate is increased in inflammation, infection, cancer, rheumatic diseases and diseases of the blood and bone marrow. Also called erythrocyte sedimentation rate and sedimentation rate.

essential oil The scented liquid taken from some plants using steam or pressure. Essential oils are used in perfumes, soaps, and aromatherapy.

essential thrombocythemia An increased number of thrombocytes (platelets) in the blood, without a known cause. Also called essential thrombocytosis.

essential thrombocytosis An increased number of thrombocytes (platelets) in the blood, without a known cause. Also called essential thrombocythemia.

Essiac An herbal tea mixture that contains burdock root, Indian rhubarb root, sheep sorrel and slippery elm bark. It has been claimed to remove toxins from the body, make the immune system stronger, relieve pain, control diabetes, treat AIDS, reduce tumor size, increase cancer survival and improve quality of life. No clinical trial using Essiac in humans has been reported in a peer-reviewed, scientific journal, and the FDA has not approved the use of Essiac for the treatment of any medical conditions.

ester A type of chemical substance that is a combination of acid and alcohol. Esters are found in essential oils (scented liquid taken from plants).

esterified estrogen A form of estrogen that may have fewer side effects than other forms. Esterified estrogens are used to treat some types of cancer, including prostate cancer. They are also used to treat the symptoms of menopause, (such as hot flashes, vaginal dryness or heavy and painful bleeding) and osteoporosis (loss of bone mass). They belong to the family of drugs called hormone therapies.

estradiol A form of the hormone estrogen.

estramustine A combination of the hormone estradiol (an estrogen) and nitrogen mustard (an anticancer drug). Used in the palliative therapy of prostate cancer.

estrogen A type of hormone made by the body that helps develop and maintain female sex characteristics and the growth of long bones. Estrogens can also be made in the laboratory. They may be used as a type of birth control and to treat symptoms of menopause, menstrual disorders, osteoporosis and other conditions.

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

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

estrogen receptor positive ER+. Describes cells that have a protein to which the hormone estrogen will bind. Cancer cells that are ER+ need estrogen to grow, and may stop growing when treated with hormones that block estrogen from binding.

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

estrogen replacement therapy ERT. Hormones (estrogen, progesterone, or both) given to postmenopausal women or to women who have had their ovaries surgically removed. Hormones are given to replace the estrogen no longer produced by the ovaries.

etanercept A drug that is commonly used to treat arthritis. It is also being studied in the treatment of cancer, and as a treatment for loss of appetite and weight loss in cancer patients. It belongs to the family of drugs called tumor necrosis factor (TNF) antagonists.

etanidazole A drug that increases the effectiveness of radiation therapy.

ethical will A final personal message or document in which a person shares his or her thoughts, values, memories, life lessons, advice and hopes for the future. The person may also ask for forgiveness and forgive others. An ethical will is not a legal document.

ethynyluracil An anticancer drug that increases the effectiveness of fluorouracil. Also called eniluracil.

etidronate A drug that belongs to the family of drugs called bisphosphonates. Bisphosphonates are used as treatment for hypercalcemia (abnormally high levels of calcium in the blood) and for cancer that has spread to the bone (bone metastases).

etiology The cause or origin of disease.

Etopophos A drug that is used to treat testicular and small cell lung cancers, and is being studied in the treatment of other cancers. It belongs to the families of drugs called podophyllotoxin derivatives and topoisomerase inhibitors. Also called etoposide phosphate.

etoposide An anticancer drug that belongs to the families of drugs called podophyllotoxin derivatives and topoisomerase inhibitors.

etoposide phosphate A drug that is used to treat testicular and small cell lung cancers, and is being studied in the treatment of other cancers. It belongs to the families of drugs called podophyllotoxin derivatives and topoisomerase inhibitors. Also called Etopophos.

ETS Environmental tobacco smoke. Smoke that comes from the burning of a tobacco product and smoke that is exhaled by smokers (second-hand smoke). Inhaling ETS is called involuntary or passive smoking. Also called environmental tobacco smoke.

eucalyptus A type of evergreen tree that is a member of the myrtle family. Oil from the leaves is used in very small amounts in mouthwash and in medicines and candy used to treat and soothe sore throats and coughs. It has also been used in some cultures to treat many other medical problems. The scientific name is Eucalyptus globulus.

euphoria A feeling of great happiness or well-being. Euphoria may be a side effect of certain drugs.

EUS Endoscopic ultrasound. A procedure in which an endoscope is inserted into the body. An endoscope is a thin, tube-like instrument that has a light and a lens for viewing. A probe at the end of the endoscope is used to bounce high-energy sound waves (ultrasound) off internal organs to make a picture (sonogram). Also called endosonography.

euthanasia An easy or painless death, or the intentional ending of the life of a person suffering from an incurable or painful disease at his or her request. Also called mercy killing.

evaluable disease Disease that cannot be measured directly by the size of the tumor but can be evaluated by other methods specific to a particular clinical trial.

evaluable patients Patients whose response to a treatment can be measured because enough information has been collected.

everolimus A substance that is being studied in the treatment of cancer. It belongs to the families of drugs called immunosuppressive agents and antiangiogenesis agents.

Ewing's family of tumors EFTs. A group of cancers that includes Ewing's tumor of bone (ETB or Ewing's sarcoma of bone), extraosseus Ewing's (EOE) tumors, primitive neuroectodermal tumors (PNET or peripheral neuroepithelioma) and Askin's tumors (PNET of the chest wall). These tumors all come from the same type of stem cell.

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

ex vivo Outside of the living body. Refers to a medical procedure in which an organ, cells, or tissue are taken from a living body for a treatment or procedure, and then returned to the living body.

exatecan mesylate An anticancer drug that belongs to the family of drugs called topoisomerase inhibitors. Also called DX-8951f.

excision Removal by surgery.

excisional biopsy A surgical procedure in which an entire lump or suspicious area is removed for diagnosis. The tissue is then examined under a microscope.

excisional skin surgery A surgical procedure used to remove moles, cysts, skin cancer, and other skin growths using local anesthesia. To treat skin cancer, the doctor uses a scalpel to remove the entire tumor and some of the healthy tissue around it.

exemestane A drug used to treat advanced breast cancer and to prevent recurrent breast cancer in postmenopausal women who have already been treated with tamoxifen. It is also being studied in the treatment of other types of cancer. Exemestane causes a decrease in the amount of estrogen made by the body. It belongs to the family of drugs called aromatase inhibitors. Also called Aromasin.

exenteration Surgery to remove organs within a body cavity.

exisulind A drug that is being studied in the treatment and prevention of cancer. It has been shown to cause apoptosis (cell death) in cancerous and precancerous cells by acting through a group of cellular enzymes called cGMP phosphodiesterases.

Exjade A drug used to treat too much iron in the blood caused by blood transfusions. It is being studied in the treatment of myelodysplastic syndromes (a group of diseases in which the bone marrow does not make enough healthy blood cells) and other conditions. Exjade binds to extra iron in the blood. The drug and the iron are passed from the body in urine. It is a type of chelating agent. Also called Deferasirox.

exocrine cancer A type of pancreatic cancer in which malignant (cancer) cells are found in the non-insulin producing tissues of the pancreas.

exocrine pancreas cell A pancreatic cell that produces enzymes that are secreted into the small intestine. These enzymes help digest food as it passes through the gastrointestinal tract.

expanded access trial A way to provide an investigational therapy to a patient who is not eligible to receive that therapy in a clinical trial, but who has a serious or life-threatening illness for which other treatments are not available. Expanded access allows a patient to receive promising but not yet fully studied or approved cancer therapies when no other treatment option exists. Also called compassionate use trial.

experimental In clinical trials, refers to a drug (including a new drug, dose, combination, or route of administration) or procedure that has undergone basic laboratory testing and received approval from the US Food and Drug Administration (FDA) to be tested in human subjects. A drug or procedure may be approved by the FDA for use in one disease or condition, but be considered experimental in other diseases or conditions. Also called investigational.

experimental drug A substance that has been tested in a laboratory and has gotten approval from the U.S. Food and Drug Administration (FDA) to be tested in people. A drug may be approved by the FDA for use in one disease or condition but be considered experimental in other diseases or conditions. Also called an investigational drug.

exploratory surgery Surgery to look inside the body to help make a diagnosis.

extensive-stage small cell lung cancer Cancer has spread outside of the lung in which it began or to other parts of the body.

external radiation Radiation therapy that uses a machine to aim high-energy rays at the cancer. Also called external-beam radiation.

external-beam radiation Radiation therapy that uses a machine to aim high-energy rays at the cancer. Also called external radiation.

extracorporeal 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 photopheresis.

extracranial Outside of the cranium (bones that surround the brain).

extracranial germ cell tumor A rare cancer that forms in germ cells in the testicle or ovary, or in germ cells that have traveled to areas of the body other than the brain (such as the chest, abdomen or tailbone). Germ cells are reproductive cells that develop into sperm in males and eggs in females.

extract In medicine, a preparation of a substance obtained from plants, animals or bacteria and used as a drug or in drugs.

extragonadal germ cell tumor A rare cancer that develops in germ cells that are found in areas of the body other than the ovary or testicle (such as the brain, chest, abdomen or tailbone). Germ cells are reproductive cells that develop into sperm in males and eggs in females.

extrahepatic Located or occurring outside the liver.

extrahepatic bile duct The part of the common hepatic bile duct (tube that collects bile from the liver) that is outside the liver. This duct joins a duct from the gallbladder to form the common bile duct, which carries bile into the small intestine when food is being digested.

extrahepatic bile duct cancer A rare cancer that forms in the part of the bile duct that is outside the liver. The bile duct is the tube that collects bile from the liver and joins a duct from the gallbladder to form the common bile duct, which carries bile into the small intestine when food is being digested.

extrapleural pneumonectomy Surgery to remove a diseased lung, part of the pericardium (membrane covering the heart), part of the diaphragm (muscle between the lungs and the abdomen), and part of the parietal pleura (membrane lining the chest). This type of surgery is used most often to treat malignant mesothelioma.

eye cancer Cancer that forms in tissues of and around the eye. Some of the cancers that may affect the eye include melanoma (a rare cancer that begins in cells that make the pigment melanin in the eye), carcinoma (cancer that begins in tissues that cover structures in the eye), lymphoma (cancer that begins in immune system cells) and retinoblastoma (cancer that begins in the retina and usually occurs in children younger than 5 years).

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