A Study of MRI-guided High-dose Radiation Therapy in Prostate Cancer

One of the usual approaches to treating intermediate-risk prostate cancer is a type of radiation therapy called SBRT (stereotactic body radiation therapy). SBRT delivers higher than standard doses of radiation over a lower number of treatment sessions. However, there is a 20% chance that intermediate-risk prostate cancer will come back after this treatment. The purpose of this study is to find out whether giving an even higher dose (a "boost" dose) of radiation directly to the main tumor and the standard dose of radiation to the rest of the prostate may cure the cancer or prevent it from coming back for a longer period of time while causing few side effects.