Radiation therapy is used to treat cancer and other diseases. It uses high-energy particles to damage the DNA in the cancer cells. This makes the cells unable to grow or divide.

There are two main types of radiation therapy:

  • External —radiation is delivered by a machine that shoots particles at the cells from outside the body
  • Internal—radioactive materials are placed in the body near the cancer cells; this is also called implant radiation or brachytherapy

In certain cases, your doctor may recommend a combination of these. Radiation is often used with other types of treatment, such as surgery, chemotherapy, and immunotherapy, which stimulates the immune system to fight infection.

This fact sheet will focus on internal radiation therapy.

This procedure is done to:

  • Control the growth or spread of cancer
  • Attempt to cure cancer
  • Reduce pain or other symptoms caused by cancer—called palliative radiation

Radiation therapy is used to treat solid tumors such as prostate cancer, breast cancer, and head and neck cancers.