Post-prostatectomy Radiation Therapy--Moderate Versus Ultra-hypofractionated (Also Known as Stereotactic Body Radiation Therapy [SBRT])

Inclusion Criteria: * Men age ≥ 18 with histologically confirmed prostate cancer after radical prostatectomy with a PSA ≥ 0.1 ng/mL * Interval between prostatectomy and planned radiation therapy start date ≥ 6 months * KPS ≥ 70 * Patients with equivocal pelvic lymph nodes on imaging are eligible if the nodes are ≤ 1.5 cm in the short axis (equivocal evidence of metastatic disease outside of the pelvis on standard imaging requires documented negative biopsy) * Ability to complete the EPIC-26 quality of life questionnaire * Ability to obtain tissue from radical prostatectomy specimen for review by Michigan Medicine Pathology * Ability to understand and the willingness to sign a written informed consent. Exclusion Criteria: * Prior history of pelvic radiation therapy * History of moderate/severe or active Crohn's disease or ulcerative colitis * History of bladder neck or urethral stricture * Evidence of distant metastatic disease or nodal involvement beyond the common iliac vessels * Initiation of androgen deprivation therapy with a LHRH / GnRH agonist or antagonist greater than 6 months prior to enrollment or receipt of any non-LHRH / GnRH agonist or antagonist androgen deprivation or anti-androgen therapy * History of another invasive malignancy within the previous 3 years except for adequately treated squamous or basal cell skin cancer * Any condition that in the opinion of the investigator would preclude participation in this study