Metformin use improves the survival of diabetic combined small-cell lung cancer patients.

Metformin has been reported having potential anticancer effect on kinds of solid tumors, but its role in combined small-cell lung cancer (C-SCLC) remains indistinct. This study aimed to explore whether metformin use has a prognosis benefit in diabetic C-SCLC patients. A total of 259 C-SCLC patients with diabetes were enrolled in our study. The clinicopathological parameters and survival data were collected and analyzed. The correlation between metformin use and clinicopathological characters was analyzed. Univariate and multivariate analyses were performed to investigate the prognostic significance of metformin use for C-SCLC. The metformin was used in 120 (46.3 %) patients. Our data showed that the metformin use decreased C-SCLC recurrence rate (p = 0.001). The median overall survival (OS) and disease-free survival (DFS) were significantly better in the metformin use group compared to non-metformin group (OS 19.0 vs 11.5 months, p < 0.001; DFS 10.5 vs 7.0 months, p < 0.001). Multivariate analyses indicated that metformin use was an independent prognostic factor for OS and DFS (p = 0.001 vs p = 0.018). The metformin use improved the long-term outcome of C-SCLC patients with diabetes, which might be considered a potential useful prognostic indicator and anticancer drug.