Benefit of Consolidation Thoracic Radiotherapy in Extensive-Stage Small-Cell Lung Cancer Patients Treated with Immunotherapy: Data from Slovenian Cohort

Background: Chemoimmunotherapy (CT/IO) with immune checkpoint inhibitors has recently become the standard of care for extensive-stage small cell lung cancer (ES-SCLC). Given the uncertain role of consolidation thoracic radiotherapy (cTRT) in this setting, we conducted a real-world study to evaluate the efficacy and safety of cTRT in ES-SCLC patients receiving first-line CT/IO. Methods: We performed a retrospective analysis of ES-SCLC patients treated with first-line CT/IO in Slovenia from December 2019 to June 2024. Patient characteristics, treatment patterns, survival outcomes, and adverse events were analyzed, with subgroup comparisons based on cTRT administration. Results: Among 208 patients (median age: 66), median overall survival was 12.1 months (95% CI: 10.6–13.7). cTRT was administered to 46 patients (22.1%), who had fewer metastases and received more maintenance IO cycles. cTRT was associated with improved OS (17.0 vs. 10.8 months; HR = 0.51, p = 0.005) and was an independent OS predictor (HR = 0.55, p = 0.013). Grade ≥3 adverse events were similar (21.7% vs. 21.3%), though pneumonitis occurred more frequently with cTRT (6.5% vs. 0%, p = 0.001). Conclusion: cTRT may improve survival in ES-SCLC patients treated with CT/IO, with no significant increase in toxicity apart from pneumonitis. Further prospective studies are needed.