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Glossary of Cancer Terms

H

H. pylori Helicobacter pylori. A type of bacteria that causes inflammation and ulcers in the stomach or small intestine. People with H. pylori infections may be more likely to develop cancer in the stomach, including MALT (mucosa-associated lymphoid tissue) lymphoma. Also called Helicobacter pylori.

hA20 A monoclonal antibody that is being studied in the treatment of refractory B-cell non-Hodgkin's lymphoma. Monoclonal antibodies are made in the laboratory and can locate and bind to cancer cells. hA20 binds to the protein CD20, which is found on B cells (a type of immune system cell), and some types of lymphoma cells. Also called IMMU-106 and HCD20.

HAART Highly active antiretroviral therapy. Treatment for human immunodeficiency virus (HIV) infection that uses a combination of several antiretroviral drugs. The drugs inhibit the ability of the virus to multiply in the body, and they slow down the development of AIDS. Also called highly active antiretroviral therapy.

hair follicle A shaft or opening on the surface of the skin through which hair grows.

hairy cell leukemia A rare type of leukemia in which abnormal B-lymphocytes (a type of white blood cell) are present in the bone marrow, spleen, and peripheral blood. When viewed under a microscope, these cells appear to be covered with tiny hair-like projections.

halofuginone hydrobromide A substance that is being studied for its ability to slow the growth of connective tissue and prevent the growth of new blood vessels to a solid tumor. It belongs to the family of drugs called quinazolinone alkaloids.

Halsted radical mastectomy Surgery for breast cancer in which the breast, chest muscles, and all of the lymph nodes under the arm are removed. For many years, this was the breast cancer operation used most often, but it is used rarely now. Doctors consider radical mastectomy only when the tumor has spread to the chest muscles. Also called radical mastectomy.

hamartoma A benign (noncancerous) growth made up of an abnormal mixture of cells and tissues normally found in the area of the body where the growth occurs.

hand-foot syndrome 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 palmar-plantar erythodysthesia.

happy major Arctium lappa. A plant whose seeds and root have been used in some cultures to treat certain medical problems. It may have antioxidant effects. Also called burdock and lappa.

hard palate The front, bony part of the roof of the mouth.

hawthorn fruit The fruit of the hawthorn tree or bush. It has been used in some cultures to treat certain medical problems, including heart problems and gastrointestinal problems.

HCA Heterocyclic amine. A chemical that is formed when meat, poultry, or fish is cooked at high temperatures, such as frying, broiling, and barbecuing. HCAs are carcinogens (substances that may cause cancer). Also called heterocyclic amine.

HCD20 A monoclonal antibody that is being studied in the treatment of refractory B-cell non-Hodgkin's lymphoma. Monoclonal antibodies are made in the laboratory and can locate and bind to cancer cells. HCD20 binds to the protein CD20, which is found on B cells (a type of immune system cell), and some types of lymphoma cells. Also called IMMU-106 and hA20.

HCP Healthcare proxy. A type of advance directive that gives a person (such as a relative, lawyer, or friend) the authority to make healthcare decisions for another person. It becomes active when that person loses the ability to make decisions for himself or herself. Also called healthcare proxy.

hCRF Human corticotropin-releasing factor. A substance being studied in the treatment of brain cancer. It is made naturally by the hypothalamus (a part of the brain) and can also be made in the laboratory. hCRF may help reduce symptoms caused by edema (swelling) of the brain. It is a type of neurohormone. Also called human corticotropin-releasing factor.

HDAC inhibitor Histone deacetylase inhibitor. A substance that causes a chemical change that stops tumor cells from dividing. HDAC inhibitors are being studied in the treatment of cancer. Also called histone deacetylase inhibitor.

HDR High-dose radiation. An amount of radiation that is greater than that given in typical radiation therapy. HDR is precisely directed at the tumor to avoid damaging healthy tissue, and may kill more cancer cells in fewer treatments. Also called high-dose radiation.

head and neck cancer Cancer that arises in the head or neck region (in the nasal cavity, sinuses, lip, mouth, salivary glands, throat, or larynx [voice box]).

healing touch A form of complementary and alternative medicine based on the belief that a vital energy flows through the human body. This energy is said to be balanced or made stronger by practitioners who pass their hands over a patient's body. Healing touch is being studied in patients receiving cancer treatments to find out if it can improve quality of life, boost the immune system or reduce side effects.

healthcare proxy HCP. A type of advance directive that gives a person (such as a relative, lawyer, or friend) the authority to make healthcare decisions for another person. It becomes active when that person loses the ability to make decisions for himself or herself. Also called HCP.

heart cancer A rare cancer that develops in tissues of the heart. Also called cardiac sarcoma.

Hedyotis diffusa An herb used in traditional Chinese medicine to treat certain medical problems. It has been used to boost the immune system and may have anticancer effects.

helical computed tomography A detailed picture of areas inside the body. The pictures are created by a computer linked to an X-ray machine that scans the body in a spiral path. Also called spiral CT scan.

Helicobacter pylori H. pylori. A type of bacteria that causes inflammation and ulcers in the stomach or small intestine. People with H. pylori infections may be more likely to develop cancer in the stomach, including MALT (mucosa-associated lymphoid tissue) lymphoma. Also called H. pylori.

helper T cell A type of white blood cell that helps stimulate immune system reactions. Helper T cells help activate cytotoxic T cells and macrophages by secreting cytokines. They also stimulate B cells to make antibodies.

hemagglutinin-neuraminidase A protein found in the outer coat of paramyxoviruses. This protein helps virus particles bind to cells, making infection easier.

hemangiopericytoma A type of cancer involving blood vessels and soft tissue.

hemangiosarcoma A type of cancer that begins in the cells that line blood vessels.

hematogenous Originating in the blood or spread through the bloodstream.

hematologic cancer A cancer of the blood or bone marrow, such as leukemia or lymphoma.

hematologist A doctor who specializes in treating blood disorders.

hematoma A pool of clotted or partially clotted blood in an organ, tissue, or body space, usually caused by a broken blood vessel.

hematopoiesis The forming of new blood cells.

hematopoietic growth factor A group of proteins that causes blood cells to grow and mature.

hematopoietic tissue Tissue in which new blood cells are formed.

hematoporphyrin derivative A drug used in photodynamic therapy that is absorbed by tumor cells. When exposed to light, it becomes active and kills the cancer cells.

hematuria Blood in the urine.

hemilaryngectomy An operation to remove one side of the larynx (voicebox).

hemochromatosis A condition in which the body absorbs more iron from food than it needs. The extra iron is stored in and may damage the liver, heart, and pancreas. It may cause organ failure, cancer, heart problems, and liver disease. Hemochromatosis may also cause bronze skin, diabetes, pain in the joints and abdomen, tiredness and impotence.

hemoglobin The substance inside red blood cells that binds to oxygen and carries it from the lungs to the tissues.

hemophagocytic lymphohistiocytosis HLH. A rare disorder in which histiocytes and lymphocytes (types of white blood cells) build up in organs including the skin, spleen and liver, and destroy other blood cells. HLH may be inherited or caused by certain conditions or diseases, including infections, immunodeficiency (inability of the body to fight infections) and cancer. Also called HLH.

hemophilia Group of hereditary disorders in which affected individuals fail to make enough of certain proteins needed to form blood clots.

hemoptysis Coughing or spitting up blood from the respiratory tract.

hemorrhage In medicine, loss of blood from damaged blood vessels. A hemorrhage may be internal or external, and usually involves a lot of bleeding in a short time.

hemorrhoid An enlarged or swollen blood vessel, usually located near the anus or the rectum.

heparin A drug that helps prevent blood clots from forming. It belongs to the family of drugs called anticoagulants (blood thinners).

hepatectomy Surgery to remove all or part of the liver.

hepatic Refers to the liver.

hepatic arterial infusion A procedure to deliver chemotherapy directly to the liver. Catheters are put into an artery in the groin that leads directly to the liver, and drugs are given through the catheters.

hepatic arterial occlusion A block in blood flow to the liver. It can happen while giving chemotherapy through a catheter in the hepatic artery. Sometimes doctors use drugs or other agents to cause hepatic arterial occlusion on purpose. This block of blood flow to the liver helps kill cancer cells growing in the liver.

hepatic artery The major blood vessel that carries blood to the liver.

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

hepatic veno-occlusive disease A condition in which some of the veins in the liver are blocked. It is sometimes a complication of high-dose chemotherapy given before a bone marrow transplant and is marked by increases in weight, liver size and blood levels of bilirubin.

hepatitis Disease of the liver causing inflammation. Symptoms include an enlarged liver, fever, nausea, vomiting, abdominal pain and dark urine.

hepatitis A vaccine A vaccine used to prevent infection with the hepatitis A virus, which causes a serious liver disease. The vaccine is made of a weakened form of the virus that cannot cause disease but causes the body’s immune system to make antibodies that destroy the hepatitis A virus.

hepatitis A virus A virus that causes a serious liver disease. It is usually spread by contact with an infected person’s stool by eating food he or she has handled after not washing hands, but it can be spread in other ways. Symptoms of infection include jaundice, dark urine and fever and other flu-like symptoms.

hepatitis B virus A virus that causes hepatitis (inflammation of the liver). It is carried and passed to others through blood or sexual contact. Also, infants born to infected mothers may become infected with the virus.

hepatitis C virus A virus that causes hepatitis (inflammation of the liver). It is carried and passed to others through blood or sexual contact. Also, infants born to infected mothers may become infected with the virus.

hepatobiliary Having to do with the liver, bile ducts and/or gallbladder.

hepatoblastoma A type of liver tumor that occurs in infants and children.

hepatocellular carcinoma A type of adenocarcinoma, the most common type of liver tumor.

hepatocyte A liver cell.

hepatoma A liver tumor.

hepatomegaly Enlarged liver.

HER1 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 ErbB1.

HER2/neu Human epidermal growth factor receptor 2 . The HER2/neu protein is involved in the growth of some cancer cells. Also called human epidermal growth factor receptor 2 and c-erbB-2 .

HER2/neu gene The gene that makes the human epidermal growth factor receptor 2. The protein produced is HER2/neu, which is involved in the growth of some cancer cells. Also called c-erbB-2.

herba Scutellaria barbatae An herb used in traditional Chinese medicine to treat certain medical problems. It may have anticancer effects.

herbal Having to do with plants.

herbal medicine A type of medicine that uses roots, stems, leaves, flowers, or seeds of plants to improve health, prevent disease and treat illness.

herbicide A chemical that kills plants.

Herceptin A monoclonal antibody that binds to HER2 (human epidermal growth factor receptor), and can kill HER2-positive cancer cells. Monoclonal antibodies are made in the laboratory and can locate and bind to cancer cells. Herceptin is used to treat breast cancer that is HER2-positive and has spread after treatment with other drugs. It is also used with other anticancer drugs to treat HER2-positive breast cancer after surgery. Herceptin is also being studied in the treatment of other types of cancer. Also called trastuzumab.

hereditary Transmitted from parent to child by information contained in the genes.

hereditary leiomyomatosis and renal cell cancer syndrome HLRCC. A rare inherited disorder that increases the risk of developing benign (noncancerous) tumors of the skin and the uterus (leiomyomas) and malignant (cancerous) tumors of the uterus (leiomyosarcoma) and the kidney. Also called HLRCC.

hereditary mutation A gene change in the body's reproductive cells (egg or sperm) that becomes incorporated into the DNA of every cell in the body of offspring; hereditary mutations are passed on from parents to offspring. Also called germline mutation.

hereditary nonpolyposis colon cancer HNPCC. An inherited disorder in which affected individuals have a higher-than-normal chance of developing colorectal cancer and certain other types of cancer, often before the age of 50. Also called HNPCC and Lynch syndrome.

herpesvirus A member of the herpes family of viruses.

heterocyclic amine HCA. A chemical that is formed when meat, poultry or fish is cooked at high temperatures, such as frying, broiling and barbecuing. HCAs are carcinogens (substances that may cause cancer). Also called HCA.

heterogeneous Made up of elements or ingredients that are not alike.

heterogenic Derived from a different source or species. Also called heterogenous.

heterogenous Derived from a different source or species. Also called heterogenic.

hexyl 5-aminolevulinate A substance that is used to find and kill tumor cells. It enters tumor cells and becomes activated when exposed to a special type of light. A chemical reaction causes the cells to produce fluorescent light and die.

HHV8 Human herpesvirus 8. A type of herpesvirus that may cause Kaposi's sarcoma (a rare cancer that can cause skin lesions) and a type of lymphoma (cancer that begins in the lymph system), especially in patients who have a weak immune system. Also called human herpesvirus 8, Kaposi’s sarcoma-associated herpesvirus and KSHV.

high blood pressure A blood pressure of 140/90 or higher. High blood pressure usually has no symptoms. It can harm the arteries and cause an increase in the risk of stroke, heart attack, kidney failure, and blindness. Also called hypertension.

high grade When referring to cancerous and precancerous growths, a term used to describe cells that look abnormal under a microscope. These cells are more likely to grow and spread quickly than cells in low-grade cancerous and precancerous growths.

high-dose chemotherapy An intensive drug treatment to kill cancer cells, but that also destroys the bone marrow and can cause other severe side effects. High-dose chemotherapy is usually followed by bone marrow or stem cell transplantation to rebuild the bone marrow.

high-dose radiation HDR. An amount of radiation that is greater than that given in typical radiation therapy. HDR is precisely directed at the tumor to avoid damaging healthy tissue, and may kill more cancer cells in fewer treatments. Also called HDR.

high-dose-rate remote brachytherapy A type of internal radiation treatment in which the radioactive source is removed between treatments. Also called high-dose-rate remote radiation therapy or remote brachytherapy.

high-dose-rate remote radiation therapy A type of internal radiation treatment in which the radioactive source is removed between treatments. Also called high-dose-rate remote brachytherapy or remote brachytherapy.

high-energy photon therapy A type of radiation therapy that uses high-energy photons (units of light energy). High-energy photons penetrate deeply into tissues to reach tumors while giving less radiation to superficial tissues such as the skin.

high-grade lymphoma A type of lymphoma that grows and spreads quickly, and has severe symptoms. It is seen frequently in patients who are HIV-positive (AIDS-related lymphoma). Also called aggressive lymphoma and intermediate-grade lymphoma.

high-grade squamous intraepithelial lesion HSIL. A precancerous condition in which the cells of the uterine cervix are moderately or severely abnormal. Also called HSIL.

high-risk cancer Cancer that is likely to recur (come back), or spread.

highly active antiretroviral therapy HAART. Treatment for human immunodeficiency virus (HIV) infection that uses a combination of several antiretroviral drugs. The drugs inhibit the ability of the virus to multiply in the body, and they slow down the development of AIDS. Also called HAART.

hilar Refers to the area where nerves and blood vessels attach to an organ.

histamine dihydrochloride A drug being studied for its ability to enhance the effectiveness of IL-2 in treating acute myeloid leukemia.

histiocytic lymphoma An outdated term referring to non-Hodgkin's lymphomas made up of large abnormal lymphoid cells. Histiocytic lymphomas include mature B-cell and T-cell non-Hodgkin's lymphomas. Many tumors that were once called histiocytic lymphomas are now considered to be a type of large cell lymphoma.

histologic examination The examination of tissue specimens under a microscope.

histology The study of tissues and cells under a microscope.

histone A type of protein found in chromosomes. Histones bind to DNA, help give chromosomes their shape, and help control the activity of genes.

histone deacetylase HDAC. An enzyme that changes the way histone binds to DNA. HDAC inhibitors are being studied as a treatment for cancer.

histone deacetylase inhibitor HDAC inhibitor. A substance that causes a chemical change that stops tumor cells from dividing. HDAC inhibitors are being studied in the treatment of cancer. Also called HDAC inhibitor.

histopathology The study of diseased cells and tissue using a microscope.

historic cohort study A research study in which the medical records of 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) are compared for a particular outcome (such as lung cancer). Also called a retrospective cohort study.

historical control subject An individual treated in the past and used in a comparison group when researchers analyze the results of a clinical study that had no control group. The use of a control, or comparison, group helps researchers determine the effects of a new treatment more accurately.

HIV Human immunodeficiency virus. The cause of acquired immunodeficiency syndrome (AIDS). Also called human immunodeficiency virus.

HIV antibody A substance produced by certain white blood cells in reaction to contact with HIV, the human immunodeficiency virus.

HIV positive Infected with the human immunodeficiency virus (HIV), the cause of acquired immunodeficiency syndrome (AIDS).

HLA Human lymphocyte antigen. One of a group of proteins found on the surface of white blood cells and other cells that play an important part in the body's immune response to foreign substances. These antigens vary from person to person, and an HLA test is done before organ transplantation to find out if tissues match between a donor and a recipient. Also called human lymphocyte antigen and human leukocyte antigen.

HLH Hemophagocytic lymphohistiocytosis. A rare disorder in which histiocytes and lymphocytes (types of white blood cells) build up in organs including the skin, spleen, and liver, and destroy other blood cells. HLH may be inherited or caused by certain conditions or diseases, including infections, immunodeficiency (inability of the body to fight infections) and cancer. Also called hemophagocytic lymphohistiocytosis.

HLRCC Hereditary leiomyomatosis and renal cell cancer syndrome. A rare inherited disorder that increases the risk of developing benign (noncancerous) tumors of the skin and the uterus (leiomyomas) and malignant (cancerous) tumors of the uterus (leiomyosarcoma) and the kidney. Also called hereditary leiomyomatosis and renal cell cancer syndrome.

HMG-CoA reductase inhibitor Hydroxymethylglutaryl-coenzyme A reductase inhibitor. A substance that blocks an enzyme needed by the body to make cholesterol and lowers the amount of cholesterol in the blood. HMG-CoA reductase inhibitor drugs are called statins. Also called hydroxymethylglutaryl-coenzyme A reductase inhibitor.

HNPCC Hereditary nonpolyposis colon cancer. An inherited disorder in which affected individuals have a higher-than-normal chance of developing colorectal cancer and certain other types of cancer, often before the age of 50. Also called hereditary nonpolyposis colon cancer and Lynch syndrome.

Hodgkin's disease A cancer of the immune system that is marked by the presence of a type of cell called the Reed-Sternberg cell. Symptoms include the painless enlargement of lymph nodes, spleen, or other immune tissue. Other symptoms include fever, weight loss, fatigue, or night sweats. Also called Hodgkin's lymphoma.

Hodgkin's lymphoma A cancer of the immune system that is marked by the presence of a type of cell called the Reed-Sternberg cell. Symptoms include the painless enlargement of lymph nodes, spleen or other immune tissue. Other symptoms include fever, weight loss, fatigue or night sweats. Also called Hodgkin's disease.

holmium Ho 166 DOTMP A drug containing a radioactive isotope that is used in the diagnosis and treatment of cancer.

holy thistle Cnicus benedictus. A plant whose leaves, stems and flowers have been used in some cultures to treat certain medical problems. Holy thistle may have anti-inflammatory and anticancer effects. Also called blessed thistle, St. Benedict's thistle, cardin and spotted thistle.

homeopathic medicine An alternative approach to medicine based on the belief that natural substances, prepared in a special way and used most often in very small amounts, restore health. According to these beliefs, in order for a remedy to be effective, it must cause in a healthy person the same symptoms being treated in the patient. Also called homeopathy.

homeopathy An alternative approach to medicine based on the belief that natural substances, prepared in a special way and used most often in very small amounts, restore health. According to these beliefs, in order for a remedy to be effective, it must cause in a healthy person the same symptoms being treated in the patient. Also called homeopathic medicine.

homeostasis A state of balance among all the body systems needed for the body to survive and function correctly. In homeostasis, body levels of acid, blood pressure, blood sugar, electrolytes, energy, hormones, oxygen, proteins, and temperature are constantly adjusted to respond to changes inside and outside the body, to keep them at a normal level.

homeostatic Having to do with homeostasis, which is a state of balance among all the body systems, needed for the body to function correctly.

homoharringtonine An anticancer drug that belongs to the plant alkaloid family of drugs.

hormonal 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, hormone treatment or endocrine therapy.

hormone A chemical made by glands in the body. Hormones circulate in the bloodstream and control the actions of certain cells or organs. Some hormones can also be made in a laboratory.

hormone receptor A protein on the surface of a cell that binds to a specific hormone. The hormone causes many changes to take place in the cell.

hormone receptor test A test to measure the amount of certain proteins, called hormone receptors, in cancer tissue. Hormones can attach to these proteins. A high level of hormone receptors may mean that hormones help the cancer grow.

hormone replacement therapy HRT. Hormones (estrogen, progesterone, or both) given to women after menopause to replace the hormones no longer produced by the ovaries. Also called HRT and menopausal hormone therapy.

hormone responsive In oncology, describes cancer that responds to hormone treatment.

hormone 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 hormonal therapy, hormone treatment or endocrine therapy.

hormone treatment 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 hormonal therapy, hormone therapy or endocrine therapy.

Horner's syndrome A condition in which one side of the face is flushed, does not produce sweat, and has a constricted pupil and drooping eyelid. It can be caused by an injury to, or paralysis of, nerves in the neck, or by a tumor.

hospice A program that provides special care for people who are near the end of life and for their families, either at home, in freestanding facilities or within hospitals.

host cell A cell that is infected by a virus or another type of microorganism.

hot flash A sudden, temporary onset of body warmth, flushing, and sweating (often associated with menopause).

hot nodule When radioactive material is used to examine the thyroid with a scanner, nodules that collect more radioactive material than the surrounding thyroid tissue are considered "hot." Hot nodules are rarely malignant. Hot nodules are sometimes called hyperfunctioning nodules.

hotspot In genetics, an area of DNA that is likely to mutate (change).

HPPH 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a. A drug that is used in photodynamic therapy that is absorbed by tumor cells; when exposed to light, it becomes active and kills the cancer cells.

HPV Human papillomavirus. A member of a family of viruses that can cause abnormal tissue growth (for example, genital warts) and other changes to cells. Infection with certain types of HPV increases the risk of developing cervical cancer. Also called human papillomavirus.

HPV vaccine Human papillomavirus vaccine. A vaccine being studied in the prevention of human papillomavirus infection and cervical cancer. Infection with certain types of HPV increases the risk of developing cervical cancer. Also called human papillomavirus vaccine.

HRT Hormone replacement therapy. Hormones (estrogen, progesterone, or both) given to women after menopause to replace the hormones no longer produced by the ovaries. Also called hormone replacement therapy and menopausal hormone therapy.

HSIL High-grade squamous intraepithelial lesion. A precancerous condition in which the cells of the uterine cervix are moderately or severely abnormal. Also called high-grade squamous intraepithelial lesion.

HTLV-1 A type of virus that infects T cells (a type of white blood cell) and can cause leukemia and lymphoma. HTLV-1 is spread by sharing syringes or needles used to inject drugs, through blood transfusions, through sexual contact, and from mother to child at birth or through breast-feeding. Also called human T-cell leukemia virus type 1.

hu14.18-interleukin-2 fusion protein An anticancer drug in which hu14.18, a monoclonal antibody, is combined with interleukin-2. The monoclonal antibody binds to the cancer cells and delivers IL-2, which stimulates the immune system to destroy the cancer cells.

Hu3S193 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. Hu3S193 binds to the protein Lewis(y), which is found on colon, breast, lung, ovary and prostate cancer cells.

Huang Lian A Chinese herb that has been used as a treatment for a variety of medical problems. It is being studied as an anticancer drug.

huC242-DM4 A substance being studied in the treatment of some types of cancer. It is made by linking the monoclonal antibody huC242 to a toxic substance called maytansinoid DM4. The monoclonal antibody locates and binds to the surfaces of cancer cells and the maytansinoid DM4 enters the cells and blocks their growth. It is a type of immunotoxin. Also called maytansinoid DM4-conjugated humanized monoclonal antibody huC242.

HuHMFG1 A monoclonal antibody that binds to the protein MUC1, which is found on breast, ovarian, pancreatic, gastric and colon cancer cells. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells. HuHMFG1 is being studied in the treatment of some types of cancer.

human corticotropin-releasing factor hCRF. A substance being studied in the treatment of brain cancer. It is made naturally by the hypothalamus (a part of the brain) and can also be made in the laboratory. hCRF may help reduce symptoms caused by edema (swelling) of the brain. It is a type of neurohormone. Also called hCRF.

human epidermal growth factor receptor 2 HER2/neu. The HER2/neu protein is involved in growth of some cancer cells. Also called HER2/neu and c-erbB-2.

human herpesvirus 8 HHV8. A type of herpesvirus that may cause Kaposi's sarcoma (a rare cancer that can cause skin lesions) and a type of lymphoma (cancer that begins in the lymph system), especially in patients who have a weak immune system. Also called HHV8, Kaposi’s sarcoma-associated herpesvirus, and KSHV.

human immunodeficiency virus HIV. The cause of acquired immunodeficiency syndrome (AIDS). Also called HIV.

human leukocyte antigen HLA. One of a group of proteins found on the surface of white blood cells and other cells that play an important part in the body's immune response to foreign substances. These antigens vary from person to person, and an HLA test is done before organ transplantation to find out if tissues match between a donor and a recipient. Also called HLA and human lymphocyte antigen.

human lymphocyte antigen HLA. One of a group of proteins found on the surface of white blood cells and other cells that play an important part in the body's immune response to foreign substances. These antigens vary from person to person, and an HLA test is done before organ transplantation to find out if tissues match between a donor and a recipient. Also called HLA and human leukocyte antigen.

human papillomavirus HPV. A member of a family of viruses that can cause abnormal tissue growth (for example, genital warts) and other changes to cells. Infection with certain types of HPV increases the risk of developing cervical cancer. Also called HPV.

human papillomavirus vaccine HPV vaccine. A vaccine being studied in the prevention of human papillomavirus infection and cervical cancer. Infection with certain types of HPV increases the risk of developing cervical cancer. Also called HPV vaccine.

human T-cell leukemia virus type 1 A type of virus that infects T cells (a type of white blood cell) and can cause leukemia and lymphoma. HTLV-1 is spread by sharing syringes or needles used to inject drugs, through blood transfusions, through sexual contact, and from mother to child at birth or through breast-feeding. Also called HTLV-1 .

humidifier A machine that puts moisture in the air.

Hurthle cell neoplasm An uncommon type of thyroid tumor that can be benign or malignant.

Hycamtin A drug used to treat certain types of ovarian cancer, lung cancer and cervical cancer. Hycamtin belongs to the family of drugs called topoisomerase inhibitors. Also called topotecan and topotecan hydrochloride.

hydatidiform mole A condition in women of childbearing age in which grape-like cysts grow in the uterus after conception (fertilization of an egg by a sperm). Hydatidiform moles may change into a type of cancer called choriocarcinoma or gestational trophoblastic tumor. Also called molar pregnancy.

hydration Combining with water.

hydrazine sulfate A substance that has been studied as a treatment for cancer and as a treatment for cachexia (body wasting) associated with advanced cancer.

hydrocephalus The abnormal buildup of cerebrospinal fluid in the ventricles of the brain.

hydrocortisone A drug used to relieve the symptoms of certain hormone shortages and to suppress an immune response.

hydrogen peroxide A chemical used in bleaches, dyes, cleansers, antiseptics, and disinfectants. In a concentrated form, it is toxic and irritating to tissues.

hydrolysis A chemical reaction that uses water to break down a compound.

hydromorphone A drug used to relieve pain.

hydronephrosis Abnormal enlargement of a kidney, which may be caused by blockage of the ureter (such as by a kidney stone) or chronic kidney disease that prevents urine from draining into the bladder.

hydroureter Abnormal enlargement of the ureter caused by any blockage that prevents urine from draining into the bladder.

hydroxychloroquine A substance that decreases immune responses in the body. It is used to treat some autoimmune diseases, and is being studied as a treatment for graft-versus-host disease. Hydroxychloroquine belongs to the family of drugs called antiprotozoals.

hydroxymethylglutaryl-coenzyme A reductase inhibitor HMG-CoA reductase inhibitor. A substance that blocks an enzyme needed by the body to make cholesterol and lowers the amount of cholesterol in the blood. HMG-CoA reductase inhibitor drugs are called statins. Also called HMG-CoA reductase inhibitor.

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

hygiene The science of health, and the practice of cleanliness that promotes good health and well-being.

hyperactivity A higher than normal level of activity. Hyperactivity can be used to describe the increased action of a body function, such as hormone production, or behavior. A person who is hyperactive may seem to be always moving or fidgeting, impulsive, unable to concentrate and talking too much.

hyperalimentation A form of nutrition that is delivered into a vein. Hyperalimentation 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 hyperalimentation. Also called parenteral nutrition, total parenteral nutrition and TPN.

hyperbaric oxygen Oxygen that is at an atmospheric pressure higher than the pressure at sea level. Breathing hyperbaric oxygen to enhance the effectiveness of radiation therapy is being studied.

hypercalcemia Abnormally high blood calcium.

hyperfractionated radiation therapy A way of giving radiation therapy in smaller-than-usual doses two or three times a day instead of once a day. Also called hyperfractionation and superfractionated radiation therapy.

hyperfractionation A way of giving radiation therapy in smaller-than-usual doses two or three times a day instead of once a day. Also called hyperfractionated radiation therapy and superfractionated radiation therapy.

hyperglycemia Abnormally high blood sugar.

Hypericum perforatum St. John's wort. An herbal product sold as an over-the-counter treatment for depression. It is being studied for its ability to lessen certain side effects of cancer treatment.

hyperkeratosis A condition marked by thickening of the outer layer of the skin, which is made of keratin (a tough, protective protein). It can result from normal use (corns, calluses), chronic inflammation (eczema) or genetic disorders (X-linked ichthyosis, ichthyosis vulgaris).

hypernephroma The most common type of kidney cancer. It begins in the lining of the renal tubules in the kidney. The renal tubules filter the blood and produce urine. Also called renal cell cancer.

hyperparathyroidism A condition in which the parathyroid gland (one of four pea-sized organs found on the thyroid) makes too much parathyroid hormone. This causes a loss of calcium from the bones and an increased level of calcium in the blood. Symptoms include bone pain and kidney problems.

hyperplasia An abnormal increase in the number of cells in an organ or tissue.

hypersensitivity An exaggerated response by the immune system to a drug or other substance.

hypertension A blood pressure of 140/90 or higher. Hypertension usually has no symptoms. It can harm the arteries and cause an increase in the risk of stroke, heart attack, kidney failure and blindness. Also called high blood pressure.

hyperthermia Abnormally high body temperature. This may be caused as part of treatment, by an infection or by exposure to heat.

hyperthermia therapy A type of treatment in which body tissue is exposed to high temperatures to damage and kill cancer cells or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs.

hyperthermic perfusion A procedure in which a warmed solution containing anticancer drugs is used to bathe, or is passed through the blood vessels of, the tissue or organ containing the tumor.

hyperthyroidism Too much thyroid hormone. Symptoms include weight loss, chest pain, cramps, diarrhea and nervousness. Also called overactive thyroid.

hyperuricemia A buildup of uric acid (a byproduct of metabolism) in the blood; a side effect of some anticancer drugs.

hypervascular Having a large number of blood vessels.

hypnosis A trance-like state in which a person becomes more aware and focused and is more open to suggestion.

hypogammaglobulinemia A condition in which the level of immunoglobulins (antibodies) in the blood is low and the risk of infection is high.

hypoglycemia Abnormally low blood sugar.

hypopharyngeal cancer Cancer that forms in tissues of the hypopharynx (the bottom part of the throat). The most common type is squamous cell carcinoma (cancer that begins in flat cells lining the hypopharynx).

hypopharynx The bottom part of the throat. Cancer of the hypopharynx is also known as hypopharyngeal cancer.

hypotension Abnormally low blood pressure.

hypothalamus The area of the brain that controls body temperature, hunger and thirst.

hypothesis A tentative proposal made to explain certain observations or facts that requires further investigation to be verified.

hypothyroidism Too little thyroid hormone. Symptoms include weight gain, constipation, dry skin and sensitivity to the cold. Also called underactive thyroid.

hypoxia A condition in which there is a decrease in the oxygen supply to a tissue. In cancer treatment, the level of hypoxia in a tumor may help predict the response of the tumor to the treatment.

hypoxic Having too little oxygen.

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

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