Hypofractionated Stereotactic Body Radiation Therapy for Patients With Prostate Cancer That Was Removed by Surgery

Inclusion Criteria: * Adenocarcinoma of the prostate treated primarily with radical prostatectomy * Any type of radical prostatectomy is permitted including retropubic, perineal, laparoscopic or robotically assisted; there is no time limit for the date of radical prostatectomy * One of the following pathologic classifications * T3N0 disease with or without a positive surgical margin or * T2N0 disease with or without a positive surgical margin * Those with T2N0 disease and a negative margin must have a detectable prostate-specific antigen (PSA) following radical prostatectomy or * Must have had an undetectable PSA after prostatectomy and has since had a rise in post-operative PSA to 0.2 ng/mL or greater * Zubrod performance status of 0 -1 * No distant metastases, based on the following workup within 60 days prior to registration * Magnetic resonance imaging (MRI) of the pelvis * Bone scan or sodium fluoride positron emission tomography (PET), that if suspicious has MRI or plain X-rays to rule out bone metastasis * Patients can be on androgen deprivation therapy * Ability to understand and willingness to sign a study-specific informed consent prior to study entry Exclusion Criteria: * N1 patients are ineligible, as are those with lymph node (LN) enlargement \> 1.5 cm by computed tomography (CT) or MRI of the pelvis, unless the LN is biopsy proven to be negative * Gross residual disease in the prostate fossa appreciated wither on digital rectal examination (DRE) or on imaging, unless biopsy proven not to contain cancer * Patients who were exposed to neoadjuvant chemotherapy or chemotherapy after prostatectomy * Prior radiation of any kind to the prostate gland or pelvis * Prior brachytherapy is not allowed * History of inflammatory colitis or other active severe comorbidities * Patients who are on immunosuppressant medication