title: Do androgen deprivation and the biologically equivalent dose matter in low-dose-rate brachytherapy for intermediate-risk prostate cancer?
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.
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, Japan. tabata2125@gmail.com.
authors.forename: Ryuji
authors.initials: R
authors.lastname: Tabata
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kimura
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Kuruma
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sasaki
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Kido
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Miki
authors.affiliation: Department of Pathology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Radiology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Aoki
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Egawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D014408:Biomarkers, Tumor; D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods; D003131:Combined Modality Therapy; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy*; D011868:Radioisotopes / Q000008:administration & dosage; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D000726:Androgen Antagonists; D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D011868:Radioisotopes
keywords: Androgen deprivation therapy; brachytherapy; dose-response; prostate cancer