Two decades of high dose rate brachytherapy with external beam radiotherapy for prostate cancer

High-dose-rate brachytherapy (HDR-BT) has optimal prerequisites in radiotherapy of prostate cancer (PC) with a conformal dose distribution and high doses per fraction giving a biological dose escalation. We report the outcome after HDR-BT and external beam radiotherapy (EBRT) after 20 years of experience.

The study includes 623 patients, median age of 66 years, treated from 1995 to 2008 and a median follow up of 11 years (range 2-266 months). Androgen deprivation therapy was given to 429 patients (69%). The HDR-BT was given with two 10 Gy fractions and the EBRT with 2 Gy fractions to 50 Gy.

The 10-year PC-specific survival was 100%, 92%, 91%, and 75% for low-, intermediate-, high- and very high-risk patients respectively, and the 10-year probability of PSA relapse was 0%, 21%, 33%, and 65% respectively. The 10-year actuarial prevalence for ≥grade 2 GU- and GI-toxicities were 28% and 12% respectively and for ≥grade 3, 4% and 1% respectively. Urethral stricture was the most frequent GU complication with a 10-year actuarial incidence of 10%. Treatment without dose constraints for the urethra conferred a higher incidence 18%, compared to 5% after 2003 (p < 0.001). Sixteen patients experienced grade 4 GU toxicity, of which 13 were treated before 2003. No grade 4 rectal toxicity was seen.

The combination of EBRT and HDR-BT with adequate dose constraints to risk organs provides satisfactory long-term tumour control even in high-risk patients. GI toxicity stabilised but GU toxicity progressed during the 10-year follow up.