Bladder full or empty for pelvic radiation therapy (BEFORE): A multi-center randomized controlled trial.

Abstract

TPS408 Background: Pelvic radiation therapy plays a key role in the treatment of most genitourinary (GU), gynecologic (Gyn), and gastrointestinal (GI) malignancies of the pelvis. Commonly, physicians instruct patients undergoing pelvic radiation therapy to present with a reproducibly full bladder for treatment with the hope that increasing the distance between the treatment target and normal tissues will limit toxicity. However, this is challenging for patients and often leads to uncertainties in radiation dose distribution to the adjacent pelvic organs, as the bladder volume varies during a treatment course. Retrospective data suggests that treating with an empty bladder has minimal impact on treatment-related toxicity, but prospective data is very limited. A phase III randomized trial is required to evaluate the relative merits of two bladder fill protocols in terms of safety and patient-reported outcomes. The goal of this trial is to identify the optimal bladder filling approach to minimize toxicity and maximize patient quality of life. Methods: The BEFORE trial (NCT06651697) is an investigator-initiated, multi-center, prospective, open-label, pragmatic, two-arm randomized phase III study enrolling patients undergoing pelvic radiation therapy. Patients of all genders planning to undergo pelvic radiation therapy with curative intent for a primary GU, Gyn, or GI malignancy of the pelvis are eligible. This trial aims to include 300 patients randomized to one of the two arms, empty or full bladder protocol, in a 1:1 ratio stratified by primary tumor site, treatment of lymph nodes, and prior prostatectomy. The primary endpoint is the physician-reported acute any attribution GU and/or GI grade ≥2 toxicity within 3 months post-radiation therapy. Secondary endpoints are radiation attribution acute GU and/or GI toxicity, any attribution and radiation attribution late GU and/or GI toxicity, patient-reported urinary and bowel quality of life, and percentage of treatment fractions requiring delay due to incomplete bladder filling in the full bladder arm. BEFORE has enrolled 89 of 300 planned participants. Clinical trial information: NCT06651697 .