—science concerned with defining and explaining the interrelationships of factors that determine disease frequency and distribution.


—a form of the hormone estrogen.


—the cause or origin of disease.


—based on systematically reviewed clinical research findings.


—originating outside the body.


—the growth of fibrous tissue.

first-degree relatives

—genetically-related parents, children, and full siblings.

gene therapy

—treatment that alters a gene. In studies of gene therapy for cancer, researchers are trying to improve the body’s natural ability to fight the disease or to make the cancer cells more sensitive to other kinds of therapy.

genetic testing

—analyzing DNA to look for a genetic alteration that may indicate an increased risk for developing a specific disease or disorder.


—the grade of a tumor depends on how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. Grading systems are different for each type of cancer.

hematologic cancers

—a cancer of the blood or bone marrow, such as leukemia or lymphoma. Also called hematologic malignancy.


—surgical removal of the right or left side of the colon.


—of or relating to the liver.

hormonal status

—the presence or absence of hormone receptors on the surface of cancer cells.

hormonal therapy

—treatment that adds, blocks, or removes hormones. 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.


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

incident cases

—the number of newly diagnosed cancer cases.

intestinal stricture

—abnormal narrowing of the intestines.

invasive cancer

—cancer that has spread beyond the layer of tissue in which it developed and is growing into surrounding, healthy tissues. Also called infiltrating cancer.

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