Urinary organs-at-risk for radiotherapy following radical prostatectomy: contouring guidelines on behalf of the Francophone Group of Urological Radiation Therapy (GFRU).

Abstract

Purpose: Urinary toxicity following radical prostatectomy (RP) and postoperative radiotherapy (RT) includes urinary incontinence and vesicourethral anastomosis (VUA) strictures. With the increasing use of stereotactic body radiotherapy (SBRT), dose-escalation, and reirradiation within the prostate bed (PB), standardization of the definition of urinary organs at risk (OARs) in the post-RP setting is needed. This works aims to provide a comprehensive review of the anatomical and physiopathological changes occurring after RP, as well as to provide a consensus on urinary OARs delineation for prostate cancer (PCa) EBRT in the post-RP setting.

Methods and materials: A multidisciplinary task force including three radiation oncologists, one uroradiologist, and two urologists was created in 2024. First, OARs potentially involved in urinary toxicity were identified and discussed. A literature review was performed, addressing several questions relative to surgical procedures and reconstructive strategies. A focus was also given to potential complications following RP and its impact on urinary OARs. Secondly, results were presented and discussed with a panel of radiation oncologists, members of the "Francophone Group of Urological Radiation Therapy" (GFRU). Thereafter, GFRU experts were asked to answer a dedicated questionnaire, including 26 questions on the controversial issues related to the delineation of urinary OARs.

Results: The following structures were identified as critical for RT in the post-RP setting: bladder, bladder neck, bladder trigone, VUA, membranous urethra, striated sphincter. A consensus was reached for 25 out of 26 items.

Conclusion: New clinical scenarios at risk of toxicity in the post-RP setting are arising, including especially PB reirradiation with SBRT, PB SBRT, and dose-escalated RT within the PB. This consensus highlights contemporary urinary structures in the post-RP setting. It also proposes a standardized definition of urinary OARs for the development of future clinical trials.