Efficacy of platinum agents for stage III non-small-cell lung cancer following platinum-based chemoradiotherapy: a retrospective study

Background: Platinum-based chemoradiotherapy is the standard treatment for unresectable stage III non-small-cell lung cancer (NSCLC). However, few studies have evaluated the efficacy of subsequent chemotherapy for relapsed NSCLC following platinum-based chemoradiotherapy. This study aimed to evaluate the efficacy of platinum-doublet chemotherapy as a second-line treatment for patients with unresectable stage III NSCLC. Methods: We retrospectively evaluated patients with unresectable stage III NSCLC treated with cytotoxic chemotherapy following platinum-based chemoradiotherapy who were registered in a nationwide registry NSCLC database. Patients were divided into the platinum-doublet chemotherapy (platinum) group and single-agent chemotherapy (non-platinum) group based on the type of second-line chemotherapy. Results: The platinum group (n = 119) showed significantly better overall survival (OS) than the non-platinum group (n = 201) (median OS: 21.5 vs. 10.5 months, hazard ratio [HR]: 0.54, 95% confidence interval [CI]: 0.40–0.73, p < 0.001). OS from the beginning of chemoradiotherapy was also significantly better in the platinum group than in the non-platinum group (median OS: 34.9 vs. 21.8 months, HR: 0.58, 95% CI: 0.43–0.79, p = 0.001). In the multivariate analysis, platinum-doublet chemotherapy as second-line therapy, female sex, clinical stage IIIA, and duration of ≥ 8.6 months from the beginning of first-line therapy to the beginning of second-line therapy were associated with significantly better OS. Conclusion: Platinum-doublet chemotherapy as a second-line therapy may prolong survival in unresectable stage III NSCLC patients following platinum-based chemoradiotherapy. Thus, re-administration of platinum agents may be a promising treatment for unresectable stage III NSCLC treated with platinum-based chemoradiotherapy.