The aim of the present study was to report the survival outcomes and late toxicity of high-dose-rate brachytherapy (HDRBT) boost for dose escalation in patients with intermediate-to-high-risk prostate cancer.

Retrospective data were collected from 137 patients who had undergone definitive radiotherapy for prostate cancer between 2006 and 2010. All patients had external-beam radiotherapy (median dose 46Gy) and HDRBT. Brachytherapy dose was 19Gy in two fractions (6 hours apart) with one implant using Ir-192.

There were 94 high-risk and 43 intermediate-risk patients (NCCN classification). The median follow-up period was 60 months. The 5-year biochemical progression-free survival was 92 and 76% for intermediate- and high-risk groups, respectively. Prostate cancer-specific survival for the intermediate-risk group was 100% and for the high-risk group it was 92% at 5 years. For the entire cohort, the 5-year rate of urethral stricture formation was 13%, and the 5-year rate of late grade 2 and grade 3 gastrointestinal toxicity was 4·7 and 4·6%, respectively. There was no grade 3 or greater genitourinary toxicity.

Our data add to the growing body of literature supporting the use of HDRBT in prostate cancer. Late toxicity rates were marginally higher than that expected.