Many studies established the role of metformin as an inhibitor of many kinds of tumors like pancreatic, medullary thyroid, breast, prostate, ovarian and endometrial carcinoma, in a dose-dependent manner via altering glucose metabolism, inhibiting the PI3K-AKT-mTOR signaling pathway, and promoting the apoptosis of cancer cells [43]. Here, PIK3CA is linked to thyroid gland disorder.