Daily Adaptive Post-Prostatectomy With Stereotactic Ablative Radiotherapy in Patients With Prostate Cancer

PRIMARY OBJECTIVE: I. To demonstrate the safety of daily, adaptive online replanning in patients treated with stereotactic body radiation therapy (SBRT) to the prostate +/- pelvic lymph nodes as defined by observation of a grade 3 genitourinary and gastrointestinal toxicity rate of less than or equal to 5%. SECONDARY OBJECTIVES: I. To determine the feasibility of daily, adaptive online replanning for patients receiving SBRT to the prostate fossa +/- pelvic lymph nodes. II. To assess the efficacy of daily, adaptive SBRT to the prostate fossa. III. To measure the change in patient reported urinary, bowel, and sexual outcomes following protocol treatment. EXPLORATORY OBJECTIVE: I. To assess the dosimetric benefits of daily adaptive replanning for prostate fossa/pelvic lymph node SBRT. OUTLINE: Patients are assigned to 1 of 2 groups. GROUP I: Patients undergo daily adaptive online replanning for SBRT to the prostate fossa on study. Patients also undergo (MRI) of the prostate fossa and pelvis and may undergo positron emission tomography/computed tomography (PET/CT) during screening. GROUP II: Patients undergo daily adaptive online replanning for SBRT to the prostate fossa and pelvic lymph nodes on study. Patients also undergo MRI of the prostate fossa and pelvis and may undergo PET/CT during screening.