Abstract
INTRODUCTION: Although immune checkpoint inhibitor (ICI) therapy for patients with extensive-stage small cell lung cancer (ES-SCLC) has shown promising results in clinical trials, it is not as widely used as for other cancers. Thus, investigating the association between ICI therapy and overall survival and treatment patterns of patients with ES-SCLC provides a new perspective regarding the introduction of ICI. MATERIALS & METHODS: This retrospective cohort study identified patients newly diagnosed with SCLC between January 2015 and January 2023 who received first-line treatment with etoposide from a nationwide database in Japan. Patients were divided into those who received ICI and conventional chemotherapy. Overall survival was assessed with a Cox proportional hazards model weighted by the inverse propensity score. The treatment patterns were visualized using a Sankey diagram. RESULTS: Of the 4537 patients, 2433 received conventional chemotherapy and 2104 received ICI therapy. The hazard ratio for mortality with ICI therapy was 0.892 (95% CI, 0.797-0.998). Less than half of the patients received ICI therapy as first-line treatment. Older patients tended to receive conventional chemotherapy. CONCLUSIONS: Compared with conventional chemotherapy, ICI therapy was associated with increased overall survival in patients with ES-SCLC. However, clinical implementation of ICI therapy was delayed, particularly in older patients.