Glossary of Clinical Trials Terms


Abdomen – The area of the body that contains the pancreas, stomach, intestine, liver, gallbladder and other organs.

Acute myeloid leukemia (AML) – A quickly progressing disease in which too many immature white blood cells (not lymphocytes) are found in the blood and bone marrow. Also called acute myelogenous leukemia or acute nonlymphocytic leukemia.

Acute promyelocytic leukemia – A subtype of acute myeloid leukemia.

Adjuvant therapy – Treatment given after the primary treatment to increase the chances of a cure. Adjuvant therapy may include chemotherapy, radiation therapy, hormone therapy, or biological therapy.

Adrenal glands – A pair of small glands, one located on top of each kidney. They produce steroid hormones, adrenaline and noradrenaline, which help control heart rate, blood pressure, and other important body functions.

Androgen suppression – Treatment to suppress or block the production of male hormones. Androgen suppression is achieved by surgical removal of the testicles, by taking female sex hormones, or by taking other drugs, antiandrogens. Also called androgen ablation.

Androgens – A family of hormones that promote the development and maintenance of male sex characteristics.

Anemia – A condition in which the number of red blood cells is below normal. This can cause tiredness, shortness of breath, chest pain.

Angiogenesis – Blood vessel formation. Tumor angiogenesis is the growth of blood vessels from surrounding tissue to a solid tumor. This is caused by the release of chemicals by the tumor.

Angiogenesis inhibitor – A substance that may prevent the formation of blood vessels. In anticancer therapy, and angiogenesis inhibitor prevents the growth of blood vessels from surrounding tissue to a solid tumor.

Anthracycline – A type of antibiotic that comes from the fungus Streptococcus peucetius. Anthracyclines are used as treatments for cancer. Daunorubicin, doxorubicin, and epirubicin are anthracyclines.

Antibody – A type of protein made by certain white blood cells in response to a foreign substance (antigen). Each antibody can bind to only a specific antigen. The purpose of this binding is to help destroy the antigen. Antibodies can work in several ways, depending on the nature of the antigen. Some antibodies destroy antigens directly. Others make it easier for white blood cells to destroy.

Antibody therapy – Treatment with an antibody, a substance that can directly kill specific tumor cells or stimulate the immune system to kill tumor cells.

Anticancer antibiotics – A group of anticancer drugs that block cell growth by interfering with DNA, the genetic material in cells. Also called antitumor antibiotics or antineoplastic antibiotics.

Anticoagulant – A drug that helps prevent blood clots from forming. Also called a blood thinner.

Antiestrogen – A substance that blocks the activity of estrogens, the family of hormones that promote the development and maintenance of female sex characteristics.

Antihormone therapy – Treatment with drugs, surgery, or radiation in order to block the production or action of a hormone. Antihormones therapy may be used in cancer treatment because certain hormones are able to stimulate the growth of some types of tumors.

Antimetabolite – A drug that is very similar to natural chemicals in a normal biochemical reaction in cells but different enough to interfere with the normal division and functions of cells.

Antimicrotubule agent – A drug that inhibits cell growth by stopping cell division. Antimicrotubule agents are used as treatments for cancer. Also called antimitotic agents, mitotic inhibitors, and taxanes. Docetaxel and paclitaxel are antimicrotubule agents.

Antineoplastic – A substance that blocks the formation of neoplasms (growths that may become cancerous).

Antioxidant – A substance that prevents damage caused by free radicals. Free radicals are highly reactive chemicals that often contain oxygen. They are produced when molecules are split to give products that have unpaired electrons. This process is called oxidation.

Aromatase inhibitor – A drug that prevents the formation of estradiol, a female hormone, by interfering with an aromatase enzyme. Aromatase inhibitors are used to treat a type of hormone-dependent breast cancer.

Arsenic trioxide – A substance that induces programmed cell death (apoptosis) in certain cancer cells. It belongs to the family of drugs called antineoplastics.

Atrasentan – A substance that is being studies as a treatment for cancer. It belongs to the family of drugs called endothelin-1 protein receptor antagonists.

Axilla – The underarm or armpit.

Axillary – Pertaining to the armpit area, including lymph nodes that are located there.

Axillary dissection – Surgery to remove lymph nodes found in the armpit region. Also called axillary lymph node dissection.

Axillary lymph node dissection – Surgery to remove lymph nodes found in the armpit region. Also called axillary dissection.

Axillary lymph nodes – Lymph nodes found in the armpit regions that drain lymph channels from the breast.


Biological therapy – Treatment to stimulate or restore the ability of the immune system to fight infections and other diseases. Also used to lessen side effects that may be caused by some cancer treatments. Also known as immunotherapy, biotherapy, or biological response modifier (BRM) therapy.

Biopsy – The removal of cells or tissues for examination under a microscope. When only a sample of tissue is removed, the procedure is called an incisional biopsy or core biopsy. When an entire lump or suspicious area is removed, the procedure is called an excisional biopsy. When a sample of tissue or fluid is removed with a needle, the procedure is called a needle biopsy or fine-needle aspiration.

Bone marrow – The soft, sponge-like tissue in the center of most large bones. It produces white blood cells, red blood cells, and platelets.


CCI-779 – An anticancer drug that inhibits the growth of cancer cells by preventing cell division.

Chemoprevention – The use of drugs, vitamins, or other agents to try to reduce the risk of, or delay the development or recurrence of cancer.

Chemotherapy – Treatment with anticancer drugs.

Chronic lymphocytic leukemia (CLL) – A slowly progressing disease in which too many white blood cells (called lymphocytes) are found in the body.

Colony stimulating factors – Substances that stimulate the production of blood cells. Colony-stimulating factors include granulocyte colony-stimulating factors (also called G-CSF and filgrastim), granulocyte-macrophage colony-stimulating factors (also called GM-CSF and sargramostim), and promegapoietin.

Continuous infusions – The administration of a fluid into a blood vessel, usually over a prolonged period of time.

Combination chemo – Treatment using more than one anticancer drug.

Corticosteroids – Hormones that have antitumor activity in lymphomas and lymphoid leukemias; in addition, corticosteroids (steroids) may be used for hormone replacement and for the management of some of the complications of cancer and its treatment.

Cryosurgery – Treatment performed with an instrument that freezes and destroys abnormal tissues.


Dalteparin – A drug that helps prevent the formation of blood clots; it belongs to the family of drugs called anticoagulants.

Ductal cancer in situ – DCIS. Abnormal cells that involve only the lining of a breast duct. The cells have not spread outside the duct to other tissues in the breast. Also called intraductal carcinoma.

Double blinded – A clinical trial in which neither the medical staff nor the person knows which of several possible therapies the person is receiving.


Enzymes – A protein that speeds up chemical reactions in the body.

Estrogen – Hormones that promote the development and maintenance of female sex characteristics.

Extensive stage small cell lung cancer – Cancer that has spread outside the lung to other tissues in the chest or to other parts of the body.


Gastrointestinal stromal tumor – GIST. A type of tumor that usually begins in cells in the wall of the gastrointestinal tract. It can be benign or malignant. 


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

Hormone therapy – Treatment with hormones to replace or block other 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), hormones may be given to block the body's natural hormones. Also called hormonal therapy, hormone treatment, or endocrine therapy.

Hormones – Chemicals 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.


Immune response – The activity of the immune system against foreign substances (antigens).

Infusions – A method of putting fluids, including drugs, into the bloodstream. Also called intravenous infusion.


Limited stage small-cell lung cancer – Cancer found in one lung and in nearby lymph nodes.

Locally advanced – Cancer that has spread only to nearby tissues or lymph nodes.

Lumpectomy – Surgery to remove the tumor and a small amount of normal tissue around it.


Mammography – The use of x-rays to create a picture of the breast.

Mastectomy – Surgery to remove the breast (or as much of the breast tissue as possible).

Melanoma – A form of skin cancer that arises in melanocytes, the cells that produce pigment. Melanoma usually begins in a mole.

Metastatic – Having to do with metastasis, which is the spread of cancer from one part of the body to another.

Monoclonal antibodies – Laboratory-produced substances that can locate and bind to cancer cells wherever they are in the body. Many monoclonal antibodies are used in cancer detection or therapy; each one recognizes a different protein on certain cancer cells. Monoclonal antibodies can be used alone, or they can be used to deliver drugs, toxins, or radioactive material directly to a tumor.


Non-small cell lung cancer – A group of lung cancers that includes squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. 


Observation – Closely monitoring a patient's condition but withholding treatment until symptoms appear or change. Also called watchful waiting.


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

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

Peripheral blood – Blood circulating throughout the body.

Phase I – a study that is testing the best way to give a new treatment and also collects information about the safety of the drug. Small numbers of patients take part in these studies.

Phase II – A study that focuses on whether the new treatment has an anticancer effect. Small numbers of patients take part in these studies.

Phase III – A study that compares results of people taking the new treatment with results of people taking standard treatment. Large numbers of patients take part in these studies.

Placebo – An inactive substance that looks the same as, and is administered in the same way as, a drug in a clinical trial.

Post menopausal – Refers to the time after menopause. Menopause is the time in a woman's life when menstrual periods stop permanently; also called "change of life."


Quality of Life – The overall enjoyment of life. Many clinical trials assess the effects of cancer and its treatment on the quality of life. These studies measure aspects of an individual's sense of well-being and ability to carry out various tasks.


Radiation therapy – The use of high-energy radiation from x-rays, gamma rays, neutrons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or from materials called radioisotopes. Radioisotopes produce radiation and can be placed in or near the tumor or in the area near cancer cells. This type of radiation treatment is called internal radiation therapy, implant radiation, interstitial radiation, or brachytherapy. Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that circulates throughout the body. Also called radiotherapy, irradiation, and x-ray therapy.

Randomization – A method used to prevent bias. People are assigned by chance, like the flip of a coin.

Recurrence – The return of cancer, at the same site as the original (primary) tumor or in another location, after the tumor had disappeared.

Red blood cells – RBC. A cell that carries oxygen to all parts of the body. Also called an erythrocyte.

Regimen – A treatment plan that specifies the dosage, the schedule, and the duration of treatment.


Selenium – An essential dietary mineral.

Sentinel lymph node – The first lymph node to which cancer is likely to spread from the primary tumor. Cancer cells may appear first in the sentinel node before spreading to other lymph nodes.

Stages of Cancer – the extent of a cancer and whether the disease has spread from the original site to other parts of the body.

Supratentorial glioblastoma multiforme – A type of brain cancer.


Targeted therapy – a type of treatment that uses drugs or other substances, such as monoclonal antibodies, to attack specific cancer cells without harming normal ones.

Testicles – The two egg-shaped glands found inside the scrotum. They produce sperm and male hormones. Also called testes.


Unresectable – Unable to be removed with surgery.


Vaccines – A substance or group of substances meant to cause the immune system to respond to a tumor or to microorganisms, such as bacteria or viruses. A vaccine can help the body recognize and destroy cancer cells or microorganisms.

Vitamin E – A substance used in cancer prevention. It belongs to the family of drugs called tocopherols.


White blood cells – WBC. Refers to a blood cell that does not contain hemoglobin. White blood cells include lymphocytes, neutrophils, eosinophils, macrophages, and mast cells. These cells are made by bone marrow and help the body fight infection and other diseases.


X-rays – A type of high-energy radiation. In low doses, X-rays are used to diagnose diseases by making pictures of the inside of the body. In high doses, X-rays are used to treat cancer.