External beam radiation therapy External beam radiation therapy generally involves treatments 5 days a week for 6 or 7 weeks. The treatments cause no pain, and each session lasts just a few minutes. In many cases, if the tumor is large, hormonal therapy may be started at the time of radiation therapy and continued for several years. The primary target is the prostate gland itself. Radiating the lymph nodes in the pelvis, once common practice, has not proven to produce any long-term benefits for most patients, but it may be necessary in certain circumstances.
Radiation can also cause a variety of long-term problems.
These include proctitis , inflammation of the rectum, with bleeding and bowel problems such as diarrhea, and cystitis , inflammation of the bladder, leading to problems with urination. In addition, some 40 to 50 percent of men treated with radiation therapy become impotent. Higher-energy radiation beams can be more precisely focused, while computer technology allows a radiation oncologist to tailor treatment to the anatomy of the individual patient. Internal radiation therapy Radiation can also be delivered to the prostate from dozens of tiny radioactive seeds implanted directly into the prostate gland. This approach, known as interstitial implantation or brachytherapy , has the advantage of delivering a high dose of radiation to tissues in the immediate area, while minimizing damage to healthy tissues such as the rectum and bladder.