The anticarcinogenic effects of metformin have been attributed to several mechanisms: activation of LKB1/AMPK pathway, induction of cell cycle arrest and/or apoptosis, inhibition of protein synthesis, inhibition of the unfolded protein response (UPR), activation of the immune system, and a possible eradication of cancer stem cells [16] The activation of LKB1/AMPK pathway inhibits mammalian target of rapamycin (mTOR). This evidence concerns the gene STK11 and cancer.