Retrospective analysis of postoperative adjuvant therapy and survival in T4 esophageal squamous cell carcinoma: a dual-cohort study using SEER and Chinese multicenter data

Background: T4N0-3M0 esophageal squamous cell carcinoma is traditionally considered unresectable, and definitive chemoradiotherapy remains the standard of care. Selected patients who achieve R0 resection may obtain superior survival, yet the value of adjuvant radiotherapy or chemotherapy in this setting remains undefined. Methods: = 54) to evaluate the survival impact of postoperative radiotherapy and chemotherapy in patients with resected T4N0-3M0 esophageal squamous cell carcinoma. Propensity-score matching, multivariable Cox regression, and restricted cubic spline analysis were used to assess survival outcomes and explore potential dose-response relationships. All Chinese patients received postoperative radiotherapy. Results: < 0.001). Findings remained consistent after propensity-score matching. The survival benefit was most pronounced in node-negative patients. Postoperative chemotherapy showed no significant survival advantage on multivariable analysis. Age ≥60 and lymphovascular invasion were independent poor prognostic factors in the Chinese postoperative radiotherapy cohort. Conclusion: This study generates the hypothesis that postoperative radiotherapy may be associated with improved survival in selected T4N0-3M0 ESCC patients. These observational findings cannot establish causality. Prospective randomized trials are warranted before clinical adoption.