A Study To Evaluate Hypofractionated Proton Therapy Or IMRT For Recurrent, Oligometastatic Prostate Cancer

PRIMARY OBJECTIVE: I. To assess late \>= grade 3 gastrointestinal (GI) and/or genitourinary (GU) toxicity of interest within each treatment arm, moderate hypofractionation (MHF) and conventional fractionation (CF), delivered with PBRT or IMRT (late defined as 3 to 24 months after protocol radiation therapy \[RT\]). SECONDARY OBJECTIVES: I. Late grade \>= 2 GI and/or GU toxicities of interest within 24 months after protocol treatment, using Common Terminology Criteria for Adverse Events (CTCAE) version (v)4.0. II. Acute grade \>= 3 GI and/or GU toxicities of interest during and within 3 months after the protocol treatment, using CTCAE v4.0. III. Compare the rates of late \>= grade 3 GI and/or GU toxicity between the 2 treatment schedules. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients undergo IMRT or PBRT 5 days a week over 3 weeks. Patients undergo positron emission tomography (PET) scan, computed tomography (CT) scan, magnetic resonance imaging (MRI), and blood sample collection throughout the study. ARM II: Patients undergo IMRT or PBRT 5 days a week over 5 weeks. Patients undergo PET scan, CT scan, MRI, and blood sample collection throughout the study. After completion of study, patients are followed up at 3-6, 12, 18, 24, 30, 36, 42, 48, 54, and 60 months.