Focal Brachytherapy for Localized Prostate Cancer: Systematic Review and Meta-Analysis

Abstract

Advances in image-guided brachytherapy have increased the interest in focal brachytherapy (F-BT) approaches to optimize disease control, while reducing the toxicities associated whole gland treatments for prostate cancer (PCa). In this study we performed a systematic review to report biochemical control (BC), and genitourinary (GU) and gastrointestinal (GI) toxicity rates in patients with localized prostate cancer treated with F-BT as a definitive or salvage modality. This project was registered in the PROSPERO database (ID CRD42022320921). A comprehensive literature search was conducted in Cochrane Central databases, Cochrane Database of Systematic Reviews, Embase Classic +Embase, and Medline ALL, all from the OvidSP platform and Web of Science from Clarivate, from each database's inception to July 2022. Search was restricted to English and included terms: focal brachytherapy/prostate cancer, partial brachytherapy/prostate cancer. In total, 14862 articles were identified. Manuscripts that not related to focal or partial prostate brachytherapy, review papers and studies not reporting BC were excluded. After eliminating duplicates, and studies deemed irrelevant by consensus among three independent reviewers, 44 articles remained for in-depth review and data extraction. Thirty studies that included BC outcomes were included for this analysis, comprising 1556 patients treated with F-BT for PCa. Of these, 1094 (70%) and 462 (30%) underwent F-BT as definitive monotherapy or salvage, respectively; while 585 (38%) and 971 (62%) received HDR or LDR, respectively. For F-BT as monotherapy, the most commonly prescribed dose for HDR was 19 Gy in 1 fraction (range 19-24 Gy), and for LDR, 145 Gy (90-160Gy). Whereas for salvage F-BT, most common dose schedule of HDR was 19Gy in 1 fraction (19-27GY) and LDR 145Gy (144-145Gy). BC random effects estimate for F-BT monotherapy at 1-, 2-, 3-, and 5-years were 100% (P = 1.0), 96% (P = 0.45), 91% (P = 0.45) and 87% (P< 0.01), respectively. Whereas BC random effects estimate for salvage at 1-, 2-, 3-, and 5-years were 91% (P = 0.86), 68% (0.17), and 57% (P = 0.20), respectively. GI and GU grade 3-4 crude toxicity rates for monotherapy and salvage ranged from 0-3.33% and 0-17%, respectively. Over the last decade, there has been increasing interest in F-BT approaches, both as monotherapy and in the salvage setting. BC and toxicity profiles of F-BT appear favorable, and future studies directly comparing with whole-gland treatments are warranted.