ESTRO 2025 - Abstract Book

S1232

Clinical – Lower GI

ESTRO 2025

group and non-RT group. Overall survival (OS) was measured to assess the clinical benefits of RT. Kaplan–Meier survival analysis, univariable and multivariable regression analysis were applied.

Results: A total of 666 eligible patients were finally enrolled (Fig. 1). Before matching, the median follow-up for OS was 98.0 months in overall cohorts. Totally 266 deaths had observed in the two groups, respectively. The median OS of the RT group and non-RT group were 22.0 and 13.0 months (HR 0.61, 95% CI 0.51-0.73, p < 0.001), respectively. After matching, the difference in OS remained significant (18.0 and 14.0 months, HR 0.71, 95% CI 0.59-0.86, p < 0.001). Subgroup analyses revealed significantly better results for stage Ⅱ , Ⅲ and even Ⅳ patients who received radiotherapy whatever before or after matching （ all p < 0.05). The multivariable analysis showed that radiotherapy was associated with OS (HR,0.54; 95%CI, 0.45to 0.65; p < 0.001 ）， together with distant metastasis. These results were consistent after matching （ both p < 0.05.

Fig.1 The inclusion Criteria and Screening Diagram