Risk of rectal bleeding with endorectal balloon use after hypofractionated intensity‐modulated radiotherapy for prostate cancer

OBJECTIVE: To evaluate the long-term impact of endorectal balloon (ERB) use on rectal bleeding and endoscopic changes among patients who underwent symptom-driven endoscopic evaluation after moderately hypofractionated intensity-modulated radiotherapy (IMRT) for prostate cancer. PATIENTS AND METHODS: Between 2018 and 2020, 230 patients with prostate cancer underwent definitive moderately hypofractionated IMRT with or without ERB. Endoscopic assessment was performed based on gastrointestinal symptoms or clinical judgement. Rectal toxicity was assessed clinically and graded according to the Common Terminology Criteria for Adverse Events, while endoscopic findings were scored using the Vienna Rectoscopy Score (VRS). RESULTS: The 5-year cumulative incidence of Grade ≥2 rectal bleeding was 9.0% in the non-ERB group and 27.7% in the ERB group (P < 0.001). In multivariable analysis, ERB use was independently associated with an increased risk of rectal bleeding (hazard ratio 3.45; 95% confidence interval 1.68-7.07; P < 0.001), and this association was consistent across adjusted and matched cohorts. Endoscopic evaluation showed significantly higher rates of telangiectasia, mucosal congestion, and VRS ≥3 in the ERB group, particularly during the first 3 years after radiotherapy. Temporal changes in VRS followed a quadratic trajectory, peaking at approximately 2-3 years and subsequently declining. Oncological outcomes, including biochemical failure, distant progression, and overall survival, were comparable between the groups. CONCLUSIONS: Endorectal balloon use during moderately hypofractionated IMRT was associated with significantly greater rectal bleeding, while oncological outcomes did not differ significantly. In the absence of demonstrated patient benefit, our findings do not support the routine use of ERB in contemporary prostate radiotherapy.