Radiation therapy:
Radiation therapy involves the use of high-energy rays to kill cancer cells. It is used either by itself or in combination with surgery or chemotherapy. There are two types of radiation treatments: external beam radiation therapy and internal (or interstitial) radiotherapy. In external radiation therapy, the radiation is delivered from a machine positioned outside the body. Internal radiation therapy uses a small pellet of radioactive materials placed inside the body in the area of the cancer.