Induction immunochemotherapy before definitive chemoradiotherapy versus definitive chemoradiotherapy alone in limited-stage small-cell lung cancer: a multicenter propensity score–matched analysis

The purpose of this study is to evaluate the efficacy and safety of induction immunochemotherapy before definitive chemoradiotherapy (CRT) in patients with limited-stage small-cell lung cancer (LS-SCLC). This multicenter retrospective study included patients with LS-SCLC treated with definitive CRT, with or without induction immunochemotherapy from January 2021 to July 2024. The primary endpoints were overall survival (OS) and progression-free survival (PFS). Propensity score matching (PSM) was applied to control potential confounders. Survival was analyzed with Kaplan-Meier method and log-rank tests, and Cox regression was employed for prognostic analysis. Overall, 372 patients were included: 275 received definitive CRT alone (CRT group) and 97 received induction immunochemotherapy followed by definitive CRT (I-CRT group). Before PSM, the median OS was 30.3 months in the CRT group vs. not reached (NR) in the I-CRT group, with a 2-year OS of 59.4% vs. 72.2% (P = 0.006). The median PFS was 12.0 months vs. 22.5 months, with a 2-year PFS of 27.1% vs. 47.5%, respectively (P < 0.001). After 1:1 PSM, the median OS was 24.4 months in the CRT group vs. NR in the I-CRT group, with a 2-year OS of 50.1% vs. 70.4% (P = 0.002). The median PFS was 11.8 months vs. 21.9 months, with a 2-year PFS of 25.4% vs. 45.0%, respectively (P = 0.001). There were no significant differences in adverse events between the two groups. For LS-SCLC, the addition of induction immunochemotherapy to definitive CRT significantly improves clinical outcomes without increasing toxicity.