Induction immunochemotherapy followed by definitive chemoradiotherapy for unresectable locally advanced non-small cell lung cancer: a multi-institutional retrospective cohort study.

This study aimed to evaluate the efficacy and safety of induction immunochemotherapy followed by definitive chemoradiotherapy (CRT) for unresectable locally advanced non-small cell lung cancer (LA-NSCLC). We identified unresectable stage III NSCLC patients who received induction immunochemotherapy. Overall survival (OS) and progression-free survival (PFS) were the primary endpoints. From February 2019 to August 2022, 158 patients were enrolled. Following the completion of induction immunochemotherapy, the objective response rate (ORR) and disease control rate (DCR) were 52.5% and 83.5%, respectively. The ORR of CRT was 73.5%, representing 68.4% of the total cohort. The median PFS was 17.8 months, and the median OS was 41.9 months, significantly higher than in patients who received CRT alone ( < 0.001). Patients with concurrent CRT demonstrated markedly improved PFS ( = 0.012) and OS ( = 0.017) than those undergoing sequential CRT. Additionally, those with a programmed-death ligand 1 (PD-L1) expression of 50% or higher showed significantly elevated ORRs (72.2% vs. 47.2%,  = 0.011) and superior OS (median 44.8 vs. 28.6 months,  = 0.004) compared to patients with PD-L1 expression below 50%. Hematologic toxicities were the primary severe adverse events (grade ≥ 3) encountered, with no unforeseen treatment-related toxicities. Thus, induction immunochemotherapy followed by definitive CRT demonstrated encouraging efficacy and tolerable toxicities for unresectable LA-NSCLC.