Proton Beam Therapy with or without Androgen Suppression for Prostate Cancer

Inclusion Criteria: * Histologically confirmed prostate adenocarcinoma (within 365 days of randomization) at intermediate risk for reoccurrence determined by at least one of the following: Gleason Score 7, PSA \> = 10 and \< = 20, T stage T2b - T2c * Clinical stages T1-T2c N0 M0 as staged by the treating investigator. (AJCC Criteria 7th Ed.- appendix III). * Histological evaluation of prostate biopsy with assignment of a Gleason score to the biopsy material; Gleason score must be in the range of 2-7. \> 6 cores are strongly recommended. * PSA values \< = 20 ng/ml within 90 days prior to randomization. Obtained prior to biopsy or at least 21 days after prostate biopsy. * ECOG performance status 0-1 (appendix II) assessed within 90 days of randomization. * Patients must sign IRB approved study specific informed consent. * Patients must complete all required pre-entry tests listed in section 4.0 within the specified time frames. * Patients must be able to start treatment within 56 days of randomization. * Patients must be at least 18 years old. * For brachytherapy, an IPSS ≤ 21, or ≤ 17 if patient is on medications to improve urination. * For brachytherapy, prostate volume must be less than 55cc prior to AS. Exclusion Criteria: * Pelvic lymph nodes \> 1.5 cm in greatest dimension unless the enlarged lymph node is biopsied and negative. * Previous prostate cancer surgery to include: prostatectomy, hyperthermia and cryosurgery. * Previous pelvic radiation for prostate cancer. * Previous androgen suppression therapy for prostate cancer. * Active rectal diverticulitis, Crohn's disease affecting the rectum or ulcerative colitis (non-active diverticulitis and Crohn's disease not affecting the rectum are allowed). * Prior systemic chemotherapy for prostate cancer. * History of proximal urethral stricture requiring dilatation. * Current and continuing anticoagulation with warfarin sodium (Coumadin), heparin, low- molecular weight heparin, Clopidogrel bisulfate (Plavix), or equivalent (unless it can be stopped to manage treatment related toxicity or to have a biopsy if needed). * Major medical, addictive or psychiatric illness which in the investigator's opinion, will prevent the consent process, completion of the treatment and/or interfere with follow-up. (Consent by legal authorized representative is not permitted for this study). * Evidence of any other cancer within the past 5 years and \< 50% probability of a 5 year survival. (Prior or concurrent diagnosis of basal cell or non-invasive squamous cell cancer of the skin is allowed). * History of myocardial infarction within the last 6 months.