Consolidative thoracic radiotherapy after first-line chemoimmunotherapy in extensive-stage small-cell lung cancer: a multicenter retrospective study.

Background: While consolidative thoracic radiotherapy (cTRT) is standard after chemotherapy for extensive-stage small-cell lung cancer (ES-SCLC), its role in the immunotherapy era remains unclear, and this study provides real-world evidence on its survival benefit and safety. Methods: This multicenter, retrospective cohort study included patients diagnosed with ES-SCLC who underwent first-line chemoimmunotherapy from January 2019 to October 2024. Participants were stratified by receipt of cTRT. Overall survival (OS) was the primary endpoint; secondary endpoints included progression-free survival (PFS), thoracic relapse, extrathoracic relapse lesions, and treatment-related adverse events. Survival analyses were performed using a 3-month landmark cohort as the primary analytical approach, with propensity score matching and time-dependent Cox regression as sensitivity analyses, and robustness assessed by E-value. Results: Among 171 patients (cTRT, n=91; non-cTRT, n=80; median follow-up 41.3 months), cTRT significantly improved median OS [13.4 Conclusions: The survival benefit of cTRT established in the chemotherapy era is preserved in the immunotherapy era, with higher radiation doses potentially improving PFS and GLR emerging as a potential prognostic biomarker, warranting prospective validation.