Early radiotherapy improved survival of patients with extensive-stage small cell lung cancer treated with first-line chemo-immunotherapy

Background and purpose This real-world study aimed to investigate the efficacy of early radiotherapy (RT) in ES-SCLC patients treated with first-line chemo-immunotherapy. Materials and methods ES-SCLC patients were enrolled from August 2018 to October 2023. Patients who received early radiotherapy before disease progression were defined as Early RT group, while the others, named Salvage and Non-RT (S&N RT) group. Propensity score matching (PSM) with a 1:1 ratio was performed to balance the baseline characteristics. Results In this study, 375 patients with ES-SCLC treated with first-line chemo-immunotherapy were enrolled. The median PFS was 11.4 months of the Early RT group compared to 6.1 months of the S&N RT group (HR = 0.59, 95%CI 0.45-0.77; p < 0.001). The median OS was 23.8 months of the Early RT group versus 18.0 months of the S&N RT group (HR = 0.50, 95%CI 0.34-0.73; p = 0.004). The survival benefit persisted in the PSM cohort. Furthermore, survival was significantly improved in Early RT group compared to Salvage RT group (p = 0.028), while Salvage RT group had a similar survival with Non-RT group (p = 0.868). The risk of adverse events was tolerable. The multivariate analysis also demonstrated that early radiotherapy was an independently positive predictor for PFS and OS. Conclusions Administering early radiotherapy significantly improved both PFS and OS in patients with ES-SCLC treated with first-line chemo-immunotherapy with tolerable adverse events, while salvage radiotherapy did not improve survival. This finding warrants further validation through prospective randomized studies.