Radiation therapy is the use of radiation to injure or destroy cancer cells.
Radiation is often used in specific sites in the body, such as the ovary or uterus, and is considered a local therapy affecting cancer cells only in the treated area of the body. The rays penetrate the body from the outside, and deposit energy in the tissues in its path. The rays cause injury to all cells the normal, as well as the cancerous. Some are killed, some are injured and repair themselves, and some are not affected. Normal cells are injured, but are often able to repair themselves better than cancer cells.