Radiation therapy kills cancer cells and surrounding tissues using high-energy rays or particles. It can be delivered in several ways, including brachytherapy (using seeds) and external beam radiation. Radiation therapy for prostate cancer is best delivered by experienced radiation oncologists who work in high-volume centers of excellence.
Radiation therapy may be used:
- To slow the growth of or destroy tumors in early-stage cancers confined to the prostate gland
- As an initial treatment for men with advanced or recurrent prostate cancer
- Alone or in combination with other treatments, such as hormone deprivation, in more advanced cancers that may have spread beyond the prostate
- As a way to slow cancer growth and reduce pain in cases of advanced cancer
Types of Radiation Therapy
The following types of radiation therapy may be used to treat prostate cancer:
External Beam Radiation Therapy (EBRT)
This is the most common type of radiation therapy. Prior to treatment, your radiation team will use computed tomography (CT) scans and magnetic resonance imaging (MRI) scans to map out the location of the tumor cells. During each painless treatment session, X-ray beams are focused on the targeted cancer areas. Oncologists can change the intensity of doses and radiation beams to better deliver high doses of radiation to tumor cells while delivering lower doses to surrounding healthy tissues.
Three-Dimensional Conformal Radiation Therapy (3D-CRT)
With 3D-CRT, a computer program maps out the exact location and shape of the prostate tumors. The radiation beams are aimed at the prostate cancer from different directions, reducing damage to nearby healthy tissues.
Intensity-Modulated Radiation Therapy (IMRT)
Using this sophisticated form of external beam radiation, oncologists can change the intensity and shape of the radiation beams to better target the radiation delivered to the prostate while limiting the radiation to nearby bladder and rectal tissue. Because of the treatment planning involved with this type of radiation therapy, the doctor is able to deliver far more precise, intense and effective doses of radiation with less risk of damaging surrounding tissue.
Stereotactic Body Radiation Therapy (SBRT)
Guided by advanced imaging techniques, SBRT delivers large doses of radiation over a short period of time to a precise area. SBRT is commonly referred to by the names of the machines used to deliver the radiation (e.g., Gamma Knife® or CyberKnife®).
Brachytherapy is also called seed implantation, interstitial radiation therapy or internal radiation therapy. During permanent (low dose rate) brachytherapy, tiny radioactive pellets are inserted into the prostate using needles that enter the skin between the scrotum and anus. The pellets give off radiation to destroy the cancer cells around them for several months, until the radioactive material has disappeared. Imaging technology (ultrasound, CT scans or MRI scans) is used to ensure that the seeds are placed in the proper locations.
For some patients, temporary (high dose rate) brachytherapy is used to administer higher doses of radiation through catheters placed in the prostate for a short period of time.
Radium-223 is a radioactive treatment for men with metastatic prostate cancer that no longer responds to hormone therapy. By mimicking calcium, this revolutionary treatment may improve the survival of men with metastatic prostate cancer that has spread to the bones.
More Information About Prostate Cancer Treatment from Johns Hopkins Medicine
Radical Prostatectomy vs. Radiation: How to Compare the Results
Making a decision about prostate cancer treatment is not easy. When considering radiation therapy or radical prostatectomy, one of your top concerns is seeking reassurance that your cancer will be cured following treatment.
Find out how to manage your PSA levels and your expectations after both types of treatment.
Side Effects of Radiation Therapy
The side effects of radiation therapy include bowel, urinary and erection problems. Radiation therapy may also cause fatigue or swelling/pain in the legs or genital area due to lymphedema.
When using permanent brachytherapy, there’s a small risk of the seeds moving, although this doesn’t seem to cause any negative effects. Your doctor may advise you to stay away from pregnant women or small children since your implanted seeds may give off small amounts of radiation during the active treatment period.
More About Prostate Cancer in the Health Library