Hypofractionated Proton Beam Therapy for Localized Prostate Cancer

Inclusion Criteria: * Histologically confirmed diagnosis of adenocarcinoma of the prostate within one year of study entry; evaluation can happen outside of MD Anderson as long as histological confirmation takes place at MD Anderson * History/physical examination with digital rectal examination of the prostate within 90 days prior to registration * Histological evaluation of prostate biopsy with assignment of a Gleason score to the biopsy material demonstrating Gleason score 2-7 within 365 days of registration * Clinical stage T1-2b (American Joint Committee on Cancer \[AJCC\] 7th edition) and PSA \< 20 ng/mL within 90 days prior to registration; PSA should not be obtained within 10 days after prostate biopsy * Zubrod performance status 0-1 within 90 days prior to registration * Patient must be able to provide study-specific informed consent prior to study entry * Willingness and ability to complete the EPIC questionnaire Exclusion Criteria: * Prior or concurrent invasive malignancy (except non-melanomatous skin cancer or lymphomatous/hematogenous malignancy) unless continually disease free for a minimum of 5 years * Evidence of distant metastases * Regional lymph node involvement * Previous prostatectomy, cryosurgery, or high intensity focused ultrasound (HIFU) for prostate cancer * Previous pelvic radiation or prostate brachytherapy * Active and severe medical co-morbidity defined as follows: unstable angina and/or congestive heart failure requiring hospitalization within…