Biochemical response to neoadjuvant hormonal therapy predicts long-term prostate cancer survival outcomes after high-dose-rate brachytherapy with external beam radiotherapy

We evaluated the long-term treatment outcomes and toxicities in patients with clinically localized and locally advanced prostate cancer (PC) who underwent high-dose-rate brachytherapy (HDR-BT) with external beam radiotherapy (EBRT). We retrospectively analyzed 417 patients with PC who underwent HDR-BT with EBRT. The treatment dose was 19- and 13-Gy HDR-BT in two and single fractions, respectively, both combined with external irradiation of 46 Gy in 23 fractions, and hormonal therapy (HT). The median observation period was 7.2 (range, 2.0-17.6) years. The 7-year recurrence-free, PC-specific, and overall survival rates were 93.3%, 99.1%, and 94.8%, respectively, with only six PC mortalities. Multivariable analysis showed that pre-radiotherapy prostate-specific antigen (PSA) of > 0.05 ng/mL after neoadjuvant HT was an independent poor prognostic factor of recurrence (HR, 4.44; 95% CI 1.56-12.63; p = 0.005) and overall mortality (HR, 2.20; 95% CI 1.11-4.39; p = 0.025). The 7-year cumulative incidence rate of grade >= 2 toxicities in genitourinary and gastrointestinal tracts were 15.7% and 2.0%, respectively. HDR-BT combined with EBRT shows promising disease control and tolerant toxicities for PC. Poor PSA response to neoadjuvant androgen deprivation predicts worse survival measures. These patients may require more intensive multidisciplinary treatment in combination with radiotherapy.