Effects of metformin on survival outcomes of pancreatic cancer: a meta-analysis

Background and aim: Recent epidemiological studies indicated that metformin might improve the survival of various cancers. However, its benefit on pancreatic cancer was controversial. Methods: We performed this meta-analysis to investigate the benefit of metformin on pancreatic cancer. A comprehensive literature search was performed through PubMed, Cochrane Library and Embase. Relative risk (RR) and hazard ratio (HR) with 95% confidence interval (CI) were pooled. Results: The meta-analysis of 2 randomized controlled trials including181 pancreatic patients, revealed that metformin use was not associated with an improved overall survival at 6 months (RR=0.90, 95% CI=0.67-1.21), overall survival (HR=1.19, 95% CI=0.86-1.63) and progression-free survival (HR=1.39, 95% CI=0.97-1.99). But the meta-analysis of 8 cohorts, involving 2805 pancreatic patients with diabetes, demonstrated a favorable result with improved overall survival (HR=0.78, 95% CI=0.66-0.92). Conclusions: Observations in the cohort studies supported a favorable role of metformin while the data from randomized controlled trials did not support that. Therefore, more high-quality RCTs are warranted.