Radiation therapy is a cancer treatment. It uses high doses of radiation to kill cancer cells and stop them from spreading. About half of all cancer patients receive it. The radiation may be external, from special machines, or internal, from radioactive substances that a doctor places inside your body. The type of radiation therapy you receive depends on many factors, including
Radiation therapy can damage normal cells as well as cancer cells. Treatment must be carefully planned to minimize side effects. Common side effects include skin changes and fatigue. Other side effects depend on the part of your body being treated.
Sometimes radiation is used with other treatments, like surgery or chemotherapy.
NIH: National Cancer Institute