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.

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.

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.

genetic susceptibility

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

genetic testing

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

genetic testing

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


The study of genes and heredity. Heredity is the passing of genetic information and traits (such as eye color and an increased chance of getting a certain disease) from parents to offspring.


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.


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.

genome-wide association study

A study that compares the complete DNA of people with a disease or condition to the DNA of people without the disease or condition. These studies find the genes involved in a disease and may help prevent, diagnose and treat the disease. Also called GWAS, WGA study and whole genome association study.


The complete genetic material of an organism.

genomic profile

Information about all the genes in an organism, including variations, gene expression and the way those genes interact with each other and with the environment. A genomic profile may be used to discover why some people get certain diseases while other people do not, or why people respond differently to the same medicine.

genomic test

A test that studies the genes in a cancer to learn more about its makeup and how it could affect your outcome and treatment plan. Genomic tests look at groups of genes in cancer cells to see whether they are present, absent or too active.


The study of the complete genetic material, including genes and their functions, of an organism.


An organ that makes one or more substances, such as hormones, digestive juices, sweat, tears, saliva or milk. Endocrine glands release the substances directly into the bloodstream. Exocrine glands release the substances into a duct or opening to the inside or outside of the body.

Good Clinical Practice

Also called GCP. An international set of guidelines that helps make sure that the results of a clinical trial are reliable and that the participants are protected. Good Clinical Practice covers the way a clinical trial is designed, conducted, performed, monitored, audited, recorded, analyzed and reported.


Brand name, Zoladex. A medicine that belongs to a family called gonadotropin-releasing hormone analogs. Goserelin is used to block hormone production in the ovaries or testicles. It is used in the treatment of advanced breast cancer.


A description of a tumor based 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.


A system for classifying cancer cells in terms of how abnormal they appear when examined under a microscope. The objective of a grading system is to provide information about the probable growth rate of the tumor and its tendency to spread. The systems used to grade tumors vary with each type of cancer. Grading plays a role in treatment decisions.


Brand names: Granisol, Kytril. Granisetron is a medicine used to treat nausea and vomiting caused by cancer treatment. Granisetron is a type of serotonin receptor antagonist and an antiemetic. Also called granisetron hydrochloride.

gross description

A description by a pathologist, telling what is seen on a tissue sample when it is viewed with the naked eye.