Radiotherapy uses high-energy rays to treat disease. It can be administered both externally and internally.

External radiotherapy directs high-energy x-rays to the affected area using a large machine.

Internal radiotherapy involves having radioactive material placed inside the body.

Radiotherapy acts by destroying cancer cells in the area being treated. Normal cells can also be damaged by radiotherapy, which can cause side effects. Cancer cells cannot repair themselves after radiotherapy, although in general normal cells can.

You may be given radiotherapy for different reasons. Doctors may give radiotherapy to try to destroy a tumor and cure the cancer. This is known as curative treatment. It can be used with other treatments, such as surgery or chemotherapy.

If it is not possible to cure the cancer, doctors may give you radiotherapy to help relieve your symptoms. This is called palliative treatment.

The type of radiotherapy you are given will depend on the kind of cancer you have and your individual situation.