Ultra-hypofractionated Radiation in Prostate Cancer

Inclusion Criteria: * Ability of participant to sign a written informed consent. * Diagnosed with prostate cancer, T1-T2bN0M0 GS6-7, PSA \< 20 * IPSS score \< 15 (and \< 10 if on medication for benign prostatic hypertrophy such as tamsulosin) at time of enrollment (Appendix 21.4) * Prostate volume (by US, CT or MRI measurement) \< 50 cc at time of enrollment * Androgen deprivation therapy based on clinician judgment is permitted on study * Life expectancy \> 10 years based on clinician's judgment * No other active malignancy * Age ≥ 18 years * Performance Status Eastern Cooperative Oncology Group (ECOG) 0-1 (Appendix 21.5). * Other study-specific criteria: * Men of child-bearing potential must not donate sperm while on this study and for 90 days after their last study treatment. NOTE: Acceptable forms of birth control are listed below: * One Barrier method (cervical cap with spermicide plus male condom; diaphragm with spermicide plus male condom) PLUS * Hormonal method (oral contraceptives, implants, or injections) or an intrauterine device (e.g., Copper-T). Exclusion Criteria: * Current or anticipated use of other investigational agents while participating in this study. * Psychiatric illness/social situations that would limit compliance with study requirements * Prior pelvic radiation therapy * Prior prostatectomy * Inflammatory bowel disease or connective tissue disease requiring medical management