CyberKnife® as Monotherapy or Boost SBRT for Intermediate or High Risk Localized Prostate Cancer

The primary objective of this study is to document the effectiveness of Cyberknife stereotactic body radiotherapy (SBRT) in the treatment of intermediate and high-risk localized prostate cancer defined by biochemical Disease-Free Survival (bDFS), using Phoenix and American Society of Therapeutic Radiation and Oncology (ASTRO) definitions, at 5 years. During the prostate-specific antigen era, an ever-increasing percentage of men with prostate cancer have presented with clinically localized, potentially curable disease. Although conventional treatment options are potentially curative in selected patients, these treatments also have drawbacks, including the risk of negative long-term quality of life consequences and serious complications. The CyberKnife® system is a type of radiation machine that uses a special system to precisely focus large doses of x-rays on the tumor. The device is designed to concentrate large doses of radiation onto the tumor so that injury from radiation to the nearby normal tissue will be minimal. Intermediate risk patients will be treated with either CyberKnife® Stereotactic Body Radiation Therapy (SBRT) monotherapy or CyberKnife® SBRT boost followed by Intensity Modulated Radiation Therapy (IMRT). High risk patients will be treated with CyberKnife® SBRT boost followed by IMRT. Treatment will last 4-7 days. Patients will complete the QOL questionnaires before treatment. Questionnaires will also be completed during follow-up visits at 1, 3 , 6, 12, 18, 24, 30 and 36 months then every 12 months until year 5.