Incidence and predictors of radiation proctitis or radiation cystitis after radiotherapy in patients with prostate cancer

INTRODUCTION: This study evaluated the cumulative incidences of radiation cystitis (RC) and radiation proctitis (RP) after radiotherapy (RT) for localised and metastatic prostate cancer (PCa). It also analysed potential risk factors associated with resultant emergency admissions. METHODS: Between January 2001 and January 2023, 762 patients who underwent primary RT for localised PCa and low-volume metastatic hormone-sensitive PCa, as well as salvage or adjuvant RT after prostatectomy, were retrospectively analysed. The severities of RC and RP were assessed using the Common Terminology Criteria for Adverse Events version 5.0. Severe events were defined as grade 3 or higher. RESULTS: The median follow-up time was 59 months. The 5-year/10-year cumulative incidences of RC and severe RC were 11%/20% and 6.3%/12%, respectively. Among 58 patients with severe RC, 11 (19.0%) required endoscopic haemostasis. The 5-year/10-year cumulative incidences of RP and severe RP were 20%/21% and 7.5%/8.4%, respectively. Among 57 patients with severe RP, 38 (67%) required endoscopic haemostasis. Multivariable Cox regression analysis identified adjuvant or salvage RT as a predictor of RC; primary RT was identified as a predictor of RP. A bladder volume receiving >60 Gy of >25% was identified as a predictor of RC and severe RC. A rectal volume receiving >70 Gy of >10% was identified as a predictor of RP and severe RP. Antiplatelet medication was a significant risk factor for RC, RP, and severe events. CONCLUSION: Radiation cystitis and RP are common complications of RT in patients with PCa. Comprehensive counselling regarding these potential long-term adverse effects is imperative.