Radiation therapy is used to treat prostate cancer painlessly and noninvasively. During treatment, high-energy X-rays are delivered to the prostate cancer safely and effectively. Side effects are usually minimal, and most patients return to their normal activities following each treatment. Radiation therapy serves as an effective treatment for prostate cancer, working within cancer cells to damage their ability to multiply and spread. Several factors determine candidacy for radiation therapy treatment including the stage of the cancer, potential side effects, age and overall health. Sometimes a combination of treatments is the best plan for treating prostate cancer.