Abstract: Objective  To evaluate the effect of metformin on the overall survival of pancreatic cancer patients. Methods  A systematic search was conducted  in the  published literature on studies on the association between  metformin and overall survival benefit in pancreatic cancer patients up to June 2017 from EMBase and PubMed. The identified articles were reviewed for additional references. The most adjusted risk estimates were extracted by two authors and summarized using random effects metaanalysis. The quality of the study was assessed by the NewcastleOttawa Scale (NOS)， and the study with score ≥6 was taken as the highquality study.Results  Eleven articles were included.The metaanalysis showed that  metformin treatment  can  increase the overall survival  （OS） of patients with pancreatic cancer compared with nonmetformin treatment (HR=0.85，95%CI=0.750.95，P=0.006)，and in subgroup analysis Asian countries and high quality articles also supported  this results. Conclusion  Metformin increased  the overall survival of pancreatic cancer patients compared with nonmetformin treatment.

Key words: pancreatic neoplasms;metformin, overall survival, meta analysis