Radiation therapy for prostate cancer

Radiation therapy uses high-energy rays or particles to destroy cancer cells. Radiation may be used for prostate cancer:

  • as the primary treatment to destroy cancer cells
  • after surgery to destroy cancer cells left behind and to reduce the risk of the cancer recurring (adjuvant radiation therapy)
  • after surgery if the cancer comes back around the area where the prostate gland was (salvage radiation therapy)
  • to relieve pain or to control the symptoms of advanced prostate cancer (palliative radiation therapy)


The amount of radiation given during treatment, and when and how it is given, will be different for each person.

External beam radiation therapy

Prostate cancer is usually treated with external beam radiation therapy. A machine directs radiation to the tumour and some of the surrounding tissue.

  • External beam radiation treatment may be offered to men as a primary treatment.
  • It is given after surgery (adjuvant radiation) if the tumour had spread close to or into the outer covering of the prostate.
  • It may be given for stage IV prostate cancer to relieve urinary symptoms caused by the tumour or to relieve pain caused by bone metastases.


Brachytherapy is internal radiation therapy. A radioactive material (radioactive isotope) is placed right into the tumour. The radiation kills the cancer cells over time.


Multiple radioactive implants are surgically placed right into the prostate. This is called interstitial brachytherapy. Implants can be temporary or permanent.

  • Temporary implants are removed after the desired dose of radiation is delivered.
  • Permanent implants (such as radioactive seeds) are not removed. They deliver their dose of radiation over a period of weeks or months.


Brachytherapy is used mainly for low-risk and intermediate-risk prostate cancer. Combined external beam radiation therapy and brachytherapy may be used for high-risk prostate cancer.


See a list of questions to ask your doctor about radiation therapy.




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