Cancer Dictionary – G
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 in the head or neck, 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.
gene The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.
gene deletion The total loss or absence of a gene.
gene expression (JEEN ek-SPREH-shun) The process by which a gene gets turned on in a cell to make RNA and proteins. Gene expression may be measured by looking at the RNA, or the protein made from the RNA, or what the protein does in a cell.
generic Official nonbrand names by which medicines are known. Generic names usually refer to the chemical name of the drug.
genetic (jeh-NEH-tik) Inherited; having to do with information that is passed from parents to offspring through genes in sperm and egg cells.
genetic analysis The study of a sample of DNA to look for mutations (changes) that may increase risk of disease or affect the way a person responds to treatment.
genetic marker Alteration in DNA that may indicate an increased risk of developing a specific disease or disorder.
genetic marker of susceptibility (jeh-NEH-tik… suh-SEP-tih-BIH-lih-tee) 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.
graft Healthy skin, bone, or other tissue taken from one part of the body and used to replace diseased or injured tissue removed from another part of the body.
graft-versus-host disease GVHD. A reaction of donated stem cells against the patient’s tissue. Also called GVHD.