Stereotactic Body Radiation Therapy in Treating Patients With Localized High-Risk Prostate Cancer

Inclusion Criteria: * Histologically confirmed primary non-metastatic adenocarcinoma of the prostate * Risk-group classification into the D’Amico or National Comprehensive Cancer Network (NCCN) ‘high-risk’ group, as defined by the presence of any one of the following high-risk factors: * Pre-biopsy prostate-specific antigen (PSA) \>= 20 * Biopsy Gleason score 8-10 * Clinical stage T3 * No pelvic nodal metastases (based on computed tomography \[CT\] or magnetic resonance imaging \[MRI\] findings) * No distant metastases, based upon: * CT scan or MRI of the pelvis within 120 days prior to registration * Bone scan within 120 days prior to registration; if the bone scan is suspicious, a plain x-ray and/or MRI must be obtained to rule out metastasis * Karnofsky performance status (KPS) \>= 70 * Ability to understand, and willingness to sign, the written informed consent * Patient will have opted for SBRT among definitive treatment choices Exclusion Criteria: * Patients with any evidence of distant metastases * Hormonal therapy (luteinizing hormone-releasing hormone \[LHRH\] agonist or oral anti-androgen) exceeding 4 months prior to registration * Prior cryosurgery, high intensity focused ultrasound (HIFU) or brachytherapy of the prostate * Prior pelvic radiotherapy * History of Crohn’s disease or Ulcerative colitis