Metformin Versus Sulfonylurea in Breast Cancer Risk of Diabetic Patients: A Systematic Review and Meta-Analysis

Context: Metformin has been used for diabetic patients. This medicine might decrease the risk of breast cancer. The main objective of this article was to determine the breast cancer risk in diabetic patients and its association with metformin and sulfonylurea. Evidence Acquisition: In order to gather evidences, main databases (MEDLINE, PubMed, Cochrane library, Science Direct, Trip, Google Scholar, Institute of Scientific Information (ISI), SCOPUS and EMBASE) as well as relevant websites have searched without time limitation up to June 2015. We have searched with appropriate keywords and strategies. After quality assessment of studies, consequences of risk and mortality for breast cancer have extracted. RevMan and comprehensive meta-analysis software has used, if needed, for meta-analysis. Results: A total of 423 studies, 352 studies have entered firstly and 11 studies have selected after final review. According to the signifi- cance of heterogeneity (I 2 = 94%) in these studies, meta-analysis have scrutinized by step by step removing the studies to investigate the reason of heterogeneity. So the relative risk of breast cancer was significant in favor of metformin (RR: 0.63, 95% CI (0.56 - 0.70), Pv < 0.001). Conclusions: In this study, we have concluded that the incidence of breast cancer in patients with type 2 diabetes who have used metformin might be less than who have used sulfonylurea. However, this finding should consider carefully and needed to be con- firmed with further studies.