High Dose-Rate Brachytherapy and Stereotactic Body Radiotherapy for the Treatment of Prostate Adenocarcinoma

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.