Efficacy and safety analysis according to histology for S-1 in combination with carboplatin as first-line chemotherapy in patients with advanced non-small-cell lung cancer: updated results of the West Japan Oncology Group LETS study.

Background: A phase III study (Lung Cancer Evaluation of TS-1) previously demonstrated noninferiority in terms of overall survival (OS) at interim analysis for carboplatin-S-1 compared with carboplatin-paclitaxel for first-line treatment of advanced non-small-cell lung cancer (NSCLC). Patients and methods: A total of 564 patients were randomly assigned to receive either carboplatin on day 1 plus oral S-1 on days 1-14 or carboplatin-paclitaxel on day 1 every 21 days. Updated results and post hoc subgroup analysis according to tumor histology are presented. Results: The updated analysis revealed a median OS of 15.2 months in the carboplatin-S-1 arm and 13.1 months in the carboplatin-paclitaxel arm, with a hazard ratio (HR) of 0.956 [95% confidence interval (CI) 0.793-1.151], consistent with the previous primary analysis. Median OS was 14.0 months in the carboplatin-S-1 arm and 10.6 months in the carboplatin-paclitaxel arm (HR 0.713; 95% CI 0.476-1.068) for patients with squamous cell carcinoma (SCC), with corresponding values of 15.5 and 13.9 months (HR 1.060; 95% CI 0.859-1.308) for those with non-SCC. Conclusions: These results establish the efficacy and safety of carboplatin-S-1 in patients with advanced NSCLC regardless of tumor histology.