Impact of Hydrogel Spacer on Radiation Proctitis After Prostate Cancer Radiation Therapy: A Large-Scale Claims Database Analysis.

Purpose: We evaluated the real-world utility of hydrogel spacer placement for reducing radiation proctitis following prostate cancer radiation therapy using a large-scale claims database. Methods and Materials: We analyzed male patients from a Japanese administrative claims database (DeSC Database) who initiated primary radiation therapy between July 2018 and December 2024. Propensity score weighting using the average treatment effect on the treated method was applied to balance baseline characteristics between spacer users and nonusers. The primary endpoint was the occurrence of endoscopic gastrointestinal hemostasis, and the secondary endpoint was the diagnosis of radiation proctitis. Fine-Gray models were used to estimate subdistribution hazard ratios (sHRs) with death as a competing risk. Results: Of 7860 eligible patients, 1754 (22.3%) underwent spacer placement. For the primary endpoint (endoscopic hemostasis), the spacer group showed a statistically significant lower risk (sHR 0.26; 95% CI, 0.10-0.69; Conclusions: This large-scale real-world analysis demonstrates that hydrogel spacer placement is associated with a significantly lower incidence of severe radiation proctitis requiring endoscopic hemostasis.