Radiation therapy, sometimes called radiotherapy, effectively treats cancer by using high-energy beams to pinpoint and destroy cancerous cells. Although radiation therapy is similar to an X-ray, the dose of radiation in cancer treatment is much stronger and is given over a longer period of time. Many forms of radiation are available. Your oncologist will choose the best therapy based on the type, stage and location of your cancer.

With careful planning, radiation can be directed to the cancer and away from most normal tissues. This means you may receive treatment on more than one side of your body or from different angles. You may also need more than one type of radiation, which may require the use of more than one machine.

Over 50% of cancer patients will undergo radiation therapy; for some, it will be the only cancer treatment they need. Radiation is often used in combination with other treatments. Used before or during other procedures, radiation shrinks the tumor to make surgery or chemotherapy more effective. Used afterward, it destroys any cancer cells that might remain.

There are two basic types of radiation therapy:

External beam radiation uses specialized machines to administer a high dose of radiation directly to the cancer site and a small amount of healthy tissue at the margins of the tumor. Different machines are used for tumors of various types or in different locations in the body.

Internal radiation, or brachytherapy, involves radioactive material that is implanted in the body at the tumor site. Radiation implants are small tubes, seeds or capsules filled with different types of radioactive material and sealed.