Intensity-Modulated External Beam Radiation Therapy in Treating Patients With Prostate Cancer

Inclusion Criteria: * Patients with biopsy-proven adenocarcinoma of the prostate are eligible for protocol enrollment when the following criteria are met; patients must have low, intermediate or high-risk adenocarcinoma of the prostate, as defined by the National Comprehensive Cancer Network (NCCN) criteria * A diagnostic CT scan of the abdomen and pelvis will be obtained to rule out regional disease (maximum of 60 days prior to registration) for high-risk patients only * A bone scan showing no evidence of metastatic disease is also required for patients whose prostate-specific antigen (PSA) is greater than 20 ng/ml, Gleason's sum is greater than 7, or T-stage is greater than T2b * Alkaline phosphatase within 1.5 x upper limit of normal (ULN) is required for all patients beginning hormone therapy * AST within 1.5 x ULN is required for all patients beginning hormone therapy * Bilirubin within 1.5 x ULN is required for all patients beginning hormone therapy * Karnofsky Performance score \>= 80 * Prior to registration, patients having received no more than three months treatment with anti-androgen, luteinizing hormone-releasing hormone (LHRH) agonist, or a combination of the two remain eligible for protocol treatment; the qualifying PSA for these patients will be the value recorded prior to the initiation of the hormone therapy Exclusion Criteria: * Patients with history of inflammatory bowel disease, or who require steroid or cytotoxic therapy for collagen vascular disease * Patients with a history of cancer other than skin cancer within five years of the initiation of protocol treatment * Patients with a history of pelvic irradiation for any reason