Survival benefits of postoperative radiotherapy in esophageal cancer during the immunotherapy era:a retrospective cohort study based on the SEER database and a single-center registry in China

Purpose The aim of this study was to investigate the survival benefits of postoperative radiotherapy (PORT) in patients with resectable esophageal cancer (EC) after neoadjuvant therapy in the Immunotherapy era. Methods The study was designed as a retrospective cohort study, which included a total of 733 patients with EC from the SEER database and a single-center cohort. We used propensity score matching (PSM) to equilibrate patient characteristics. The investigation incorporated Kaplan-Meier survival analysis and the Cox proportional risk regression model to assess outcomes. Results PORT did not significantly improve survival in the overall cohort, with a median overall survival of 38 months (p=0.56) in the SEER cohort and 39 months (p=0.75) in the Chinese cohort. However, in the immunotherapy subgroup, the Chinese cohort demonstrated that immunotherapy combined with PORT significantly improved survival (p=0.044).Multivariate Cox regression analysis demonstrated that patients aged 50-59 years (HR=5.93, 95% CI: 1.67-21.06) and those aged ≥70 years (HR=10.96, 95% CI:3.04-39.56) had increased survival risks compared to patients aged <50 years. Additionally, ypT3-4 stage patients exhibited a higher risk than those with ypT1-2 stage (HR=2.12, 95% CI: 1.14-3.93, p=0.017).Similar trends were observed in cT3-4 staging, R1/R2 and no immunotherapy. Lymph node metastasis also showed a progressive relationship with survival risk, with patients categorized as ypN1 (HR=1.90), ypN2 (HR=4.24), and ypN3 (HR=6.68) experiencing increasingly higher risks (p<0.05). Conclusions The collaborative effect of immunotherapy and PORT potentially enhances survival outcomes for patients with EC. However, further prospective research is essential to confirm our results.