Prognostic benefit of statin with or without metformin in elderly patients with advanced non-small cell lung cancer: A nationwide population-based outcome study.

e20661 Background: Taking statin or metformin potentially decreases chronic inflammation, which may reduce cancer mortality as well as incidence. We aimed to clarify the prognostic impact of either use of metformin or statin in elderly patients with advanced non-small cell lung cancer (NSCLC). Methods: Patients ≥ 70 years with advanced NSCLC incident from 2007 to 2012 were identified using reimbursement claims from Korea’s National Health Insurance Service Database, and exposure to metformin and/or statin documented. Median overall survival (OS) was assessed by using Kaplan-Meier methods. Cox proportional-hazards regression model was used to examine the use of metformin and/or statin on mortality. Propensity score matching method adjusted for confounding. Results: Excluding 976 patients treated by upfront EGFR tyrosine kinase inhibitor, 7298 patients receiving palliative chemotherapy were included: 949 (13.0%) had a history of statin use, 1010 (13.8%) used metformin, 255 (3.5%) used both, and 5594 (76.6%) used neither. Median OS of statin + / metformin +, statin + / metformin –, statin - / metformin +, and statin - / metformin – users was 14.5, 12.9, 11.4 and 9.9 months respectively. By multivariate analyses, metformin use was not statistically significantly associated with improved survival in statin non-user (HR 0.99; 95% CI 0.91-1.08; p= 0.819) and statin user (HR 0.99; 95% CI 0.85-1.16; p= 0.898) group. However, use of statin, regardless of metformin, was associated with improved OS (HR 0.80; 95% CI 0.74-0.86; p< 0.001). In propensity-matched cohort, survival benefit was noted not by the use of metformin (HR 0.97; 95%CI 0.85-1.11; p= 0.661) but by the use of statin (HR 0.83; 95%CI 0.73-0.95; p= 0.007). Conclusions: Our findings did not suggest the survival benefit of metformin use in elderly patients with advanced NSCLC receiving palliative chemotherapy. Use of statin may provide a survival improvement in outcomes of elderly NSCLC.