Can metformin change the prognosis of pancreatic cancer? Retrospective study for pancreatic cancer patients with pre-existing diabetes mellitus type 2

BackgroundsThe effect of metformin on survival in patients with pancreatic cancer is controversial.AimsTo investigate the beneficial effect of metformin in pancreatic cancer patients.MethodsWe retrospectively analyzed patients with pancreatic cancer and pre-existing diabetes mellitus type 2 who were treated at Severance Hospital (Seoul, South Korea) between May 2005 and December 2013.ResultsAmong 237 enrolled patients, 117 patients (49.4%) were exposed to metformin. The median overall survival was 13.7 months for the metformin group versus 8.9 months for the non-metformin group (P = 0.001) In univariate analysis, metformin exposure, low serum carbohydrate antigen 19-9 levels (<1000 U/mL), small tumor size (≤20 mm), no tail involvement, good performance status (ECOG 0 vs. 1 or 2), and resectable cancer stage were associated with favorable survival outcomes (all P < 0.05). In multivariate analysis, in addition to low serum carbohydrate antigen 19-9 levels (<1000 U/mL) and resectable cancer stage, metformin exposure was significantly associated with longer survival with a hazard ratio of 0.61 (P = 0.001). Additionally, the cumulative duration of metformin use was significantly correlated with a favorable survival outcome.ConclusionOur findings supported that metformin exposure was associated with survival benefits in patients with pancreatic cancer and pre-existing type 2 diabetes mellitus, especially among those with an advanced cancer stage.