Words to Know


A metal element that is used in magnetic resonance imaging (MRI) and other imaging methods as a contrast agent. It helps show abnormal tissue in the body, during imaging with a special machine.

Gail model

Also called Gail risk model. A computer program that uses information from an individual's personal and family medical history to estimate one's chance of developing breast cancer.

gallium scan

A procedure to detect areas of the body where cells are dividing rapidly. It is used to locate cancer cells or areas of inflammation. A very small amount of radioactive gallium is injected into a vein and travels through the bloodstream. The gallium is taken up by rapidly dividing cells in the bones, tissues and organs and is detected by a scanner.

gamma irradiation

A type of radiation therapy that uses gamma radiation. Gamma radiation is a type of high-energy radiation that is different from X-rays.

Gamma Knife therapy

A treatment using gamma rays, a type of high-energy radiation that can be tightly focused on small tumors or other lesions, so very little normal tissue receives radiation. The gamma rays are aimed at the tumor from many different angles at once, and deliver a large dose of radiation exactly to the tumor in one treatment session. This procedure is a type of stereotactic radiosurgery. Gamma Knife therapy is not a knife and is not surgery. Gamma Knife is a registered trademark of Elekta Instruments, Inc.

gamma ray

A type of high-energy radiation that is different from an X-ray.


Also called polyvinylpyrrolidone-sodium hyaluronate gel. A gel used to lessen pain from mouth sores caused by chemotherapy or radiation therapy, oral surgery, braces or disease. It forms a thin layer over the surface of the mouth and throat to prevent irritation while eating, drinking and talking.


Brand name, Gemzar. A medicine used in combination with other agents to treat breast cancer that has spread, as well as advanced ovarian cancer. Gemzar blocks the cell from making DNA and may kill cancer cells. It is a type of antimetabolite. Also called gemcitabine hydrochloride.


The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA. Most genes contain the information for making a specific protein.

gene expression profile

Information about all messenger RNAs that are made in various cell types. A gene expression profile may be used to find and diagnose a disease or condition, and to see how well the body responds to treatment. Gene expression profiles may be used in personalized medicine.

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.

general anesthesia

A temporary loss of feeling and a complete loss of awareness that feels like a very deep sleep. It is caused by special medicines or other substances called anesthetics. General anesthesia keeps individuals from feeling pain during surgery or other procedures.

generalized anxiety disorder

Also called GAD. A condition marked by excessive worry and feelings of fear, dread and uneasiness that last six months or longer. Other symptoms of generalized anxiety disorder include being restless, being tired or irritable, muscle tension, not being able to concentrate or sleep well, shortness of breath, fast heartbeat, sweating and dizziness.


Official non-brand names by which medicines are known. Generic names usually refer to the chemical name of the medicine.


Official non-brand names by which medicines are known. Generic names usually refer to the chemical name of the medicine.

genetic counseling

A communication process between a specially-trained health professional and a person concerned about the genetic risk of disease. The person's family and personal medical history may be discussed and counseling may lead to genetic testing.

genetic marker

Alteration in DNA that may indicate an increased risk of developing a specific disease or disorder.

genetic marker of susceptibility

A specific change in a person's DNA that makes the person more likely to develop certain diseases such as cancer.

genetic predisposition

An inherited increase in the risk of developing a disease. Also called genetic susceptibility.

genetic profile

Information about specific genes, including variations and gene expression, in an individual or in a certain type of tissue. A genetic profile may be used to help diagnose a disease or learn how the disease may progress or respond to treatment with medicine or radiation.