Do androgen deprivation and the biologically equivalent dose matter in low‐dose‐rate brachytherapy for intermediate‐risk prostate cancer?. (25th July 2016)

• Record Type: Journal Article
• Authors: Tabata, Ryuji; Kimura, Takahiro; Kuruma, Hidetoshi; Sasaki, Hiroshi; Kido, Masahito; Miki, Kenta; Takahashi, Hiroyuki; Aoki, Manabu; Egawa, Shin
• Is Part Of: Cancer medicine. Volume 5:Number 9(2016:Sep.)
• Page Start: 2314
• Page End: 2322
• Publication Date: 2016-07-25
• Subjects: Androgen deprivation therapy -- brachytherapy -- dose–response -- prostate cancer; 616.994005
• DOI: 10.1002/cam4.820
• Languages: English
• ISSNs: 2045-7634

Abstract

Abstract: The objective of this study was to investigate the impact of the biologically equivalent dose (BED) on treatment outcomes after iodine‐125 low‐dose‐rate brachytherapy (LDR‐BT) with or without supplemental external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT) for intermediate‐risk prostate cancer (PCa). We retrospectively evaluated 292 Japanese patients. The impact of the BED and ADT on treatment outcomes was investigated. Cox proportional hazard models were used for univariate and multivariate analysis with biological progression‐free survival (bPFS) and clinical progression‐free survival (cPFS) as the primary outcome measures. The median follow‐up was 66 months. The bPFS and cPFS rates at 5‐/7‐years were 91.6/87.7% and 95.9/94.0%, respectively. When stratified by BED levels, the bPFS rates at 5‐/7‐years were 92.1/89.3% for <178.0 Gy2, and 91.2/86.0% for ≥178.0 Gy2, respectively ( P > 0.05). Based on ADT duration, the bPFS rates at 5‐/7‐years were 89.8/83.5%, 89.7/89.7%, and 97.5/97.5% for none, 1–3 months, and 4–12 months, respectively ( P = 0.03). For the univariate analysis, the use of ADT and its duration were significant predictors for bPFS, whereas BED was not significant. A multivariate analysis did not indicate the use of ADT itself was significant, however, when covariates were accounted for by the duration of ADT, the longer use of ADT was found to significantly improve bPFS. Although cPFS was associated neither with the BED levels nor ADT duration ( P > 0.05), ADT duration had a trend of improving cPFS ( P = 0.053). The higher levels of BED did not significantly impact bPFS for intermediate‐risk PCa after LDR‐BT with or without supplemental EBRT and ADT. The longer duration of ADT could provide an additional benefit in the context of high‐dose irradiation generated by LDR‐BT. Abstract : For the patients with the intermediate‐risk prostate cancer treated by the low‐dose‐rate brachytherapy, as androgen deprivation therapy would be used longer, the better biochemical cancer control could be obtained.