The purpose of this study is to compare the effects, good and/or bad of two treatment methods on subjects and their cancer.

Proton beam radiation therapy is one of the treatments for men with prostate cancer who have localized disease. The benefit of the combination with androgen suppression is not completely understood. This study will compare the use of hypofraction proton therapy (28 treatments) alone to proton therapy with androgen suppression therapy.

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.