Radiation therapy uses high doses of radiation, such as X-rays, to destroy cancer cells. The radiation damages the genetic material of the cells so that they can't grow. Although radiation damages normal cells as well as cancer cells, the normal cells can repair themselves and function, while the cancer cells cannot.
Radiation therapy may be used alone or combined with hormonal treatment to treat prostate cancer. It is most effective in treating cancers that have not spread outside the prostate. But it also may be used if the cancer has spread to nearby tissue. Radiation is sometimes used after surgery to destroy any remaining cancer cells and to relieve pain from metastatic cancer.
Radiation is delivered in one of two ways.
Sometimes treatment combines brachytherapy with low-dose external radiation. In other cases, treatment combines surgery with external radiation.
Another kind of radiation therapy used mostly in clinical trials is proton therapy. Proton therapy uses a different type of energy (protons) rather than X-rays. This allows a higher amount of specifically directed radiation, which protects nearby healthy tissues (especially the rectum). Sometimes proton therapy is combined with X-ray therapy.
Before radiation therapy is scheduled, your doctor probably will order a bone scan and CT scan to find out whether the cancer has spread to other parts of your body. If it has, your doctor may offer you the option of a clinical trial for treatment.
Side effects may last only as long as the treatment, or they may continue and become chronic. Some side effects develop after treatment, such as erection problems. For some men, this problem gets gradually worse over the course of several years after treatment. The long-term effects of radiation therapy on the main body systems are not yet known. Side effects include:1
Radiation therapy is used for:
For early-stage prostate cancer, prostatectomy and radiation appear to work equally well. Radiation appears to work as well as prostatectomy and active surveillance for most men over 65 who have early stage prostate cancer (stages I and II, also called localized prostate cancer). For men younger than 65, treatment with surgery may help them live longer.2
For treating advanced prostate cancer that has grown beyond the prostate but not into lymph nodes or bones, external-beam radiation combined with hormone drugs can work better than surgery. This treatment often results in controlling cancer growth and in many years of disease-free survival.1
For stage III prostate cancer, there is evidence that combining radiation with hormone drugs improves survival rates.1 One study that followed men with stage III prostate cancer for 20 years after radiation therapy showed that:1
Side effects are common. Some men develop long-term problems that may have a significant impact on their quality of life. Long-term problems that can be caused by radiation treatment include:
A newer form of brachytherapy involves placing radioactive material into the prostate and then removing the material.
This technique—also called high-dose rate, or HDR, brachytherapy—uses tiny tubes that are placed through your skin into your prostate. Radioactive material is injected into the tubes, which are left in place for 5 to 15 minutes. The tubes are removed at the end of each treatment. About three brief treatments are given over 1 or 2 days.
- National Cancer Institute (2010): Prostate Cancer Treatment (PDQ)—Health Professional Version. Available online: http://www.nci.nih.gov/cancertopics/pdq/treatment/prostate/healthprofessional.
- Lu-Yao GL, et al. (2010). Outcomes of localized prostate cancer following conservative management. JAMA, 302(11): 1202–1209.
Last Revised: June 21, 2010
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