Focal Radiation Therapy (HDR-Brachytherapy) for the Treatment of Prostate Cancer

PRIMARY OBJECTIVES: I. Estimate local control. II. Estimate acute/late grade 2+ genitourinary (GU)/gastrointestinal (GI) toxicity. SECONDARY OBJECTIVES: I. Prostate specific antigen (PSA) response at 6 weeks after radiation therapy (RT), every 3 months for 24 months, every 6 months to 60 months, then every 8-12 months until 5 years. II. Clinical progression free survival/biochemical progression free survival at 5 years. III. Distant metastasis free survival. IV. Development of castration-resistant disease. V. Overall survival. VI. Changes in quality of life VIa. Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire; VIb. Expanded Prostate Cancer Index Composite Short Form (EPIC-26) questionnaire. OUTLINE: Patients undergo HDR-BT to dominant prostate lesion on day 1. Treatment repeats at least 3 weeks apart for up to 2 fractions in the absence of disease progression or unacceptable toxicity. Patients also undergo blood sample collection, multiparametric (mp) magnetic resonance imaging (MRI) and optionally prostate-specific membrane antigen (PSMA) positron emission tomography (PET) throughout the study. Additionally, patients may undergo tumor biopsy as clinically indicated throughout the study. After completion of study treatment, patients are followed up at 6 weeks, every 3 months for the first 2 years, every 6 months for years 3 and 4, then annually thereafter.