antioxidant: A substance that inhibits oxidation.
benign tumor: A group of abnormal cells that has grown out of control, sometimes forming a detectable mass. Some benign tumors eventually turn cancerous.
carcinogen: Any substance that can cause cancer.
carcinoma: A malignant tumor that arises in the tissues that line the organs of the body. Carcinomas are found in the skin, large intestine, lungs, stomach, prostate, cervix, ovaries, brain, and breasts.
carcinoma in situ: A carcinoma in its earliest stage of development before it has spread beyond its original site.
colonoscopy: Examination of the interior of the colon using a flexible viewing instrument.
free radical: An unstable oxygen molecule that can damage tissue.
gene: The basic unit of hereditary material. A gene is composed of a particular sequence of nucleic acids and found in a particular spot on a chromosome.
hormone: A chemical that is produced by endocrine glands in one part of the body and regulates the actions of other parts of the body.
hyperplasia: The growth of tissues in an organ that results in a larger but still normal appearance, such as the growth of the breasts during pregnancy; in some cases hyperplasia may indicate a precancerous condition.
immune system: The collective name for a group of cells that defend the body against infections and protect against disease, including cancer. If the immune system is suppressed with medication or damaged, the risk of cancer increases.
mammogram: A form of x-ray of the breast that can identify tissue abnormalities, including cancerous growths. Mammograms can detect breast cancer as much as two years before a lump can be felt.
metastasis: The spread of a malignant tumor from its original location to other sites in the body, usually by means of cells that break off from the tumor and travel through the bloodstream or lymph system.
oncogenes: A gene that, under certain conditions, can cause cancer.
Pap test: Named for George Papanicolaou, the physician who developed it, this test detects cervical cancer as well as the precancerous cells that might precede it.
phytochemicals: Substances in fruits and vegetables that appear to fight against cardiovascular disease and cancer.
polyp: A noncancerous growth that is found protruding from tissues. Polyps often occur in the sinuses and in the lining of the colon.
PSA test: A test that measures levels of the prostate-specific antigen (PSA), a protein that in high levels may indicate the presence of cancer.
radiation: Energy that is in the form of particles or waves, such as x-rays and gamma rays. Radiation is often used to help make a diagnosis (for example, x-rays) or as a treatment for cancer.
risk factor: Any factor that can cause a person to be more likely to develop a disease. For example, smoking is a risk factor for lung cancer.
sigmoidoscopy: Internal examination of the rectum and sigmoid colon with a tube inserted through the anus.
tumor: Any type of swelling or enlargement of tissues; most often used to describe an abnormal growth of tissue, which can be cancerous or noncancerous.
tumor suppressor genes: Genes that can prevent or suppress the development of cancer cells.
ultraviolet radiation: A type of radiation found in sunlight that can penetrate the skin and damage cells.
vitamins: Chemicals that are found in food and that are necessary to the healthful functioning of the body. Vitamins such as A, C, and E, for instance, are antioxidants that protect cells.