Hypofractionated Proton Beam Therapy for Localized Prostate Cancer

PRIMARY OBJECTIVES: I. Estimate the incidence of grade 2 gastrointestinal toxicity following the proposed treatment regimens at 2 years post-treatment. SECONDARY OBJECTIVES: I. Estimate the change in health related quality of life (HRQOL) following the proposed treatment regimen compared to pre-treatment assessment as defined by Expanded Prostate Cancer Index Composite (EPIC), Utilization of Sexual Medications/Devices, and Medical history/conditions questionnaire. II. Estimate the rates of acute toxicity of the treatment regimens. III. Estimate the rates of late toxicity at 3, 4, and 5 years post-treatment. IV. Assess the efficacy of hypo-fractionated proton beam therapy, defined by the incidence of a rising prostate-specific antigen (PSA) at 5 years. V. Determine the rate of local failure by biopsy of the prostate when objective tests, prostate-specific antigen (PSA), magnetic resonance imaging (MRI), digital rectal exam (DRE), suggest relapse. OUTLINE: Patients undergo proton beam radiation therapy in 15 fractions over 5-6 weeks. After completion of study treatment, patients are followed up every 6-12 months for 24 months and then annually until month 60.