This is a trial of 5 fraction SBRT combined with androgen deprivation therapy for patients with localized high-risk or unfavorable intermediate risk prostate cancer

Inclusion Criteria:

• Histologically confirmed primary non-metastatic adenocarcinoma of the prostate
• High-risk or unfavorable intermediate-risk as defined below:

High-risk localized prostate cancer, as defined by any one of the following factors:

Pre-biopsy or any PSA ≥20 prior to enrollment, or Gleason score 8 or higher on any biopsy core, or cT3a or higher.

Unfavorable intermediate risk localized prostate cancer, as defined as any of the following factors:

Gleason score of 4+3 or higher on any biopsy core, or Gleason score 3+4 and >50% biopsy cores positive, or The presence of any two of the following: PSA>10, cT2b-c, Gleason score 3+4 in any core

• No pelvic nodal metastases (based on CT or 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

• Age ≥ 18
• KPS ≥ 70 (or ECOG 0-2)
• Ability to understand, and willingness to sign, the written informed consent

Exclusion Criteria:

• Patients with low-risk or favorable intermediate-risk prostate cancer do not meet inclusion criteria (these patients would be eligible for SBRT off-trial as a standard of care option)
• Patients with any evidence of distant metastases
• Hormonal therapy (LHRH agonist or oral anti-androgen) exceeding 7 months prior to registration
• Prior cryosurgery, HIFU or brachytherapy of the prostate
• Prior pelvic radiotherapy
• History of Crohn's Disease or Ulcerative Colitis