Radiotherapy uses radiation, such as x-rays, gamma rays, electron beams or protons, to kill cancer cells or damage them so they cannot grow or multiply. It is a localised treatment, which means it generally only affects the part of the body where the radiation is targeted. Radiotherapy kills or damages cancer cells in the area being treated. Cancer cells begin to die within days or weeks of treatment starting and continue to die for weeks or months after it finishes.
Although the radiation can also damage healthy cells, these can usually repair themselves.You should not feel any pain during radiotherapy, but some side effects can cause pain or discomfort. Refer to the managing side effects page for more information and ways to prevent or manage side effects.