Comparison of concurrent chemoradiotherapy followed by immunotherapy and induction chemoimmunotherapy followed by radiotherapy in unresectable stage III NSCLC: a retrospective cohort study

BACKGROUND: Concurrent chemoradiotherapy followed by immune consolidation therapy (cCRT+IO, the PACIFIC regimen) is the standard treatment for unresectable stage III non-small cell lung cancer (NSCLC). However, the optimal timing of combining radiotherapy with immunotherapy remains unexplored. This study compared the efficacy and safety of induction chemoimmunotherapy followed by radiotherapy (ICT+RT) with cCRT+IO. METHODS: This study included patients with unresectable stage III NSCLC who received cCRT+IO or ICT+RT between January 2021 and August 2023. Efficacy outcomes and safety profiles were assessed. RESULTS: A total of 183 eligible patients were enrolled; 108 (59.0%) received cCRT+IO, and 75 (41.0%) received ICT+RT. The median progression-free survival (PFS) was 26.8 months in the cCRT+IO group and 16.4 months in the ICT+RT group (hazard ratio [HR] 0.66; 95%CI 0.45-0.97; p = 0.031). The median overall survival (OS) was 45.4 months in the cCRT+IO group and was not reached in the ICT+RT group (HR 0.57, 95%CI 0.32-0.99; p = 0.046). In the cCRT+IO group, the incidence of grade 3 pneumonitis was 6.48%, whereas it was 13.33% in the ICT+RT group (p = 0.116). CONCLUSION: Compared with ICT+RT, cCRT+IO demonstrated superior efficacy with a manageable safety profile in unresectable stage III NSCLC.