Radiation therapy is often used in intermediate cases of prostate cancer. Usually combined with surgery and/or hormone therapy, radiation is applied to the prostate cancer and damages the DNA of the cancer. Normal cells are able to repair this damage, but cancer cells cannot.

Side effects can include diahrrea and anal bleeding, both of which usually clear up in time. Also, urinary incontinence and impotence somtimes result.

There are two types of radiation therapy:

External beam - a beam of radiation is focused onto the prostate gland from outside the body.

Brachytherapy - small radioactive pellets are inserted via the perineum (the area between the testicles and anus) and left permanently.