I read with interest the article “Colon neoplasia in patients with type 2 diabetes on metformin: A meta-analysis” by Rokkas and Portincasa [1]. As the authors note, the mechanisms underlying the antineoplastic potential of metformin in colon neoplasia are probably manifold and not yet completely understood. Experimental data support a direct effect of metformin in antagonizing specific pathways that promote cell proliferation, motility, invasion, and migration. As Rokkas and Portincasa mention, metformin activates AMP-activated protein kinase (AMPK), leading to downregulation of the mTOR pathway that is crucial to tumor cell metabolism.
