Hypofractionated Radiation Therapy or Conventional Radiation Therapy After Surgery in Treating Patients With Prostate Cancer

PRIMARY OBJECTIVES: I. To demonstrate that hypofractionated post-prostatectomy radiotherapy (HYPORT) does not increase patient-reported gastrointestinal (GI) or genitourinary (GU) symptoms over conventionally fractionated post-prostatectomy (COPORT) at the 2-year time point. SECONDARY OBJECTIVES: I. To compare patient-reported GI symptoms using the Expanded Prostate Cancer Index Composite (EPIC)-26 at end of radiation therapy (RT) and 6, 12, 24, and 60 months from end of treatment. II. To compare patient-reported GU symptoms using the EPIC-26 at end of RT and 6, 12, 24, and 60 months from end of treatment. III. To compare time to progression (TTP) where progression is defined as the first occurrence of biochemical failure (BF), local failure, regional failure, distant metastasis (DM), institution of new unplanned anticancer treatment, or death from prostate cancer (prostate cancer specific mortality \[PCSM\]). IV. To compare freedom from biochemical failure (FFBF) and TTP rates with an alternate prostate specific antigen (PSA) \>= PSA nadir + 2 ng/mL definition of BF. V. To compare local failure, regional failure, salvage therapy (i.e. institution of new unplanned anticancer treatment), DM, PCSM, and overall survival (OS) rates. VI. Assessment of adverse events. EXPLORATORY OBJECTIVES: I. To compare utilities for health outcomes using the EuroQol five dimensions questionnaire (EQ-5D). II. Paraffin-embedded tissue block, serum, plasma, whole blood, and urine for future translational research analyses for predictors of toxicity following hypofractionated or conventionally fractionated post-prostatectomy radiotherapy. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients undergo conventional radiation therapy for 37 fractions over 7 weeks in the absence of disease progression or unacceptable toxicity. Patients may also receive androgen deprivation therapy for up to 6 months as per doctor recommendation. ARM II: Patients undergo hypofractionated radiation therapy for 25 fractions over 5 weeks in the absence of disease progression or unacceptable toxicity. Patients may also receive androgen deprivation therapy for up to 6 months as per doctor recommendation. After completion of study treatment, patients are followed up every 6 months for 2 years and every year for 3 years and thereafter.