KRAS and neoplasm: A recent study concluded that metformin users had a higher median overall survival (OS) of 29 vs 14 months and a better 5-year OS rate of 19% vs 5%.483 These studies suggest that the well-tolerated and inexpensive antidiabetic drug metformin impairs the promotion of PDAC either through direct inhibitory effects on pancreatic cells harboring an activating Kras mutation and/or indirectly through effects on the tumor microenvironment or extrapancreatic sites that sustain a chronic inflammatory state and amplify the progression of PDAC.268 However, other studies have shown no significant benefit.