Toxicity and clinical outcomes of single-fraction high-dose-rate brachytherapy combined with external beam radiotherapy for high-/very high-risk prostate cancer: A dosimetric analysis of toxicity.

Abstract

The purpose of this study was to investigate the clinical outcomes, urinary function, quality of life (QOL), and toxicities in high- or very high-risk prostate cancer patients undergoing single-fraction high-dose-rate brachytherapy (HDR-BT) with external beam radiotherapy (EBRT) and analyze the relationship between dosimetric parameters and toxicities. Between April 2014 and April 2019, 124 patients underwent 13-Gy HDR-BT followed by EBRT (46Gy/23 fractions). Urinary function and QOL were evaluated using IPSS and 7-grade QOL Scale, respectively. Biochemical progression-free survival (bPFS) was calculated. Median follow-up period was 35.8months; all patients received neoadjuvant hormonal therapy and very high-risk patients received adjuvant hormonal therapy. Only one patient developed a grade 3 toxicity (hematuria). Multivariate analysis showed the dose covering 30% of the urethral volume, bladder volume receiving 75% of the dose, and dose covering 2cc of rectum were independent predictors of acute G2 urinary frequency, acute G2 urinary retention, and late G2 rectal hemorrhage. IPSS and QOL scores significantly increased following HDR-BT and returned to baseline within 6months. The 2-year bPFS was 99.2%. The single-fraction HDR-BT with EBRT is a safe treatment for quicker recovery of urinary symptoms and QOL. The dose of at-risk organs correlated with toxicities. Single-fraction high-dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy (EBRT) for prostate cancer is a safe treatment allowing for quicker recovery of urinary symptoms and QOL. The dose of at-risk organs correlated with toxicities.