Monotherapeutic high-dose-rate brachytherapy for prostate cancer: A dose reduction trial

Abstract

PurposeTo report preliminary results of our second regimen with 45.5Gy/7 fractions aiming to reduce toxicity, compared with our first regimen with 54Gy/9 fractions, using high-dose-rate (HDR) brachytherapy as monotherapy for prostate cancer. Materials and methodsFrom 2005 through 2010, 63 patients with localized prostate cancer were treated with HDR brachytherapy alone in 45.5Gy/7 fractions for 4days. Thirty-four patients were considered as intermediate-risk and 29 as high-risk. Thirty-seven patients also received neoadjuvant and/or adjuvant hormonal therapy. Biologically effective dose assuming α/β=1.5Gy (BED1.5) was reduced from 270Gy to 243Gy, and BED3.0 from 162Gy to 144Gy, compared to previous 54Gy/9 fractions for 5days. ResultsMedian follow-up time was 42months (range 13–72). Grade 2 acute toxicities occurred in six (9.5%), late toxicities in five (7.9%) patients, and Grade 3 or higher in none. Grade 2 late gastrointestinal toxicity rate was 1.6%, compared with 7.1% for the 54Gy regimen. Three-year PSA failure-free rates for intermediate- and high-risk patients were 96% and 90%, which were comparable to 93% and 85% for the 54Gy regimen. ConclusionsCompared to the 54 Gy/9 fractions regimen, dose-reduced regimen of 45.5Gy/7 fractions using HDR brachytherapy as monotherapy preliminarily showed an equivalent or lower incidence rate for acute and late toxicities without compromising the excellent PSA failure-free rate. Further studies with more patients and longer follow-up are warranted.