Metformin in Stage IV Lung Adenocarcinoma

Interleukin-6 (IL-6) plays an important role in the pathogenesis of lung cancer. Several clinical studies show metformin could decrease IL-6 level in addition to the glucose-lowering effect. Preclinical data also reveal metformin could decrease the IL-6 production in lung cancer cells and enhance cytotoxicity of chemotherapy in animal model. Based on these findings, the purpose of this study is to determine whether metformin is effective in lowering plasma IL-6 level and improving the treatment response in patients with non-small cell lung cancer clinically. Patients with stage IV lung adenocarcinoma will be enrolled in this study and receive standard treatments for lung cancer, either chemotherapy combining cisplatin and pemetrexed or targeted therapy (Gefitinib). For patients with plasma IL-6 more than 2.0 pg/ml after 2 cycles of standard treatment, metformin will be given and titrated to 1500mg/day gradually. Plasma IL-6 level will be checked after use of metformin for 12 weeks. Tumor response to the standard treatment plus metformin will be evaluated and side effects of metformin will also be monitored.