Adjuvant immunotherapy in esophageal squamous cell carcinoma after radiotherapy: retrospective multicentric survival analysis

Summary Background Immunotherapy improves survival with manageable toxicity in esophageal cancer as neoadjuvant, first-line, or second-line therapy. However, its adjuvant role in esophageal squamous cell carcinoma (ESCC) remains uncertain. This study evaluates whether adjuvant immunotherapy enhances survival in ESCC. Methods We conducted a multicentric propensity-score matching analysis in patients with unresected ESCC who underwent radiotherapy between January 2015 and December 2024. Kaplan–Meier analysis was employed to generate survival curves, with comparisons made via the log-rank test. Univariate and multivariate-analyses employed Cox regression models. Results A total of 207 patients were enrolled. Among them, 60 patients received immunotherapy, while 147 did not receive adjuvant immunotherapy. The median overall survival (OS) was 42 months in the immunotherapy group, compared with 22.0 months in the non-immunotherapy group (HR, 0.55; 96.4%CI, 0.32 to 0.93). The median progression-free survival (PFS) was 26 months in the adjuvant immunotherapy group versus 17 months in the non-adjuvant group, showing a statistically significant difference (HR, 0.58; 95%CI, 0.36 to 0.95). After propensity score matching, the results remained consistent with the overall cohort. Compared with the non-adjuvant group, adjuvant immunotherapy significantly improved both PFS (HR, 0.49; 95%CI, 0.27 to 0.89) and OS (HR, 0.50; 95%CI, 0.29 to 0.85). Eastern Cooperative Oncology Group performance-status score, tumor stage, and maximum tumor thickness are independent prognostic factors in univariate-analyses. In multivariate-analyses, no significant prognostic factors were identified. Conclusions Patients with unresected ESCC who received adjuvant immunotherapy following radiotherapy demonstrated significantly longer OS and PFS compared to those who did not receive adjuvant immunotherapy.