PRIMARY OBJECTIVES:~I. To estimate the biochemical progression-free survival (b-PFS) at the 5-year time point after combination therapy of stereotactic body radiotherapy (SBRT) and high dose rate (HDR)-brachytherapy (BT) boost stratified by patients with intermediate and high-risk prostate cancer.~II. To estimate the rate of acute >= grade 3 patient-reported genitourinary (GU) and gastrointestinal (GI) symptoms determined within 90 days after treatment completion, respectively.~SECONDARY OBJECTIVES:~I. To estimate patient-reported GU symptoms at the end of radiotherapy and within 6, 12, 24, and 60 months from radiotherapy completion.~II. To estimate patient reported GI symptoms at the end of radiotherapy and within 6, 12, 24, and 60 months from radiotherapy completion.~III. To estimate the cumulative incidence of acute grade >= 2 GU physician-scored toxicity, as assessed by the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 scale.~IV. To estimate the cumulative incidence of acute grade >= 2 GI physician-scored toxicity, as assessed by the CTCAE version 5.0 scale.~V. To estimate the cumulative incidence of late >= 2 GU physician-scored toxicity, as assessed by the CTCAE version 5.0 scale.~VI. To estimate the cumulative incidence of late >= 2 GI physician-scored toxicity, as assessed by the CTCAE version 5.0 scale.~VII. To determine the prostate specific antigen (PSA) complete response rate (PSA nadir =< 0.3ng/mL) at 3 months following treatment of combination SBRT and HDR-BT boost regardless of testosterone recovery.~VIII. To determine clinical progression-free survival at 5-years. IX. To determine distant metastasis-free survival at 5-years. X. To determine overall survival at 5-years.~OUTLINE:~Patients undergo HDR-BT for up to 24 hours and undergo SBRT every other day or consecutive days for up to 14 consecutive chronologic days in the absence of disease progression or unacceptable toxicity.~After completion of study treatment, patients are followed up within 90 days, every 3 months for 24 months, and then every 6 months for up to 5 years.
This phase II trial investigates the effect of high dose-rate brachytherapy and stereotactic body radiotherapy in treating patients with prostate adenocarcinoma. Brachytherapy, also known as internal radiation therapy, uses radioactive material placed directly into or near a tumor to kill tumor cells. Stereotactic body radiation therapy uses special equipment to position a patient and deliver radiation to tumors with high precision. This method may kill tumor cells with fewer doses over a shorter period and cause less damage to normal tissue.