Metformin use and survival of lung cancer patients: Meta-analysis findings

Previous studies on the association between metformin use and lung cancer survival have yielded mixed results. We aimed to perform a metaanalysis to assess the association with all available studies. Relevant studies were identified by searching PubMed and EMBASE to July 2016. We calculated the summary hazard ratios (HRs) and 95% confidence intervals (CIs) using randomeffects models. Twelve cohort studies involving 124,533 participants were included in this study. The results showed that metformin use was not associated with the overall survival of lung cancer patients (HR = 0.79, 95% CI: 0.621.02). In the subgroup analyses by country or subtype of lung cancer, although a beneficial effect of metformin use on overall survival was found in patients with smallcell lung cancer or in lung patients from China, it may be inappropriate draw a final conclusion considering small sample size, low study quality, and the limited number of studies in the subgroups. Further analyses found that metformin use after diagnosis showed a beneficial effect on both over survival (HR = 0.79, 95% CI: 0.720.87) and progressionfree survival (PFS; HR = 0.62, 95% CI: 0.390.96) of lung cancer patients. In conclusion, metformin use after diagnosis is associated with improved overall survival and PFS of lung cancer patients. Nevertheless, this effect of metformin use is needed for further assessment.