MYC and cancer: Metformin (1,1-dimethylbiguanide) as the first-line oral medication for the treatment of type-2 diabetes is cheap and wildly used.3 Multiple epidemiological studies and accumulated evidences have shown that metformin may reduce cancer risk and improve cancer prognosis and survival,4, 5, 6, 7 including PCa.8, 9, 10 Our previous work indicated that metformin inhibits salivary adenocarcinoma grow in vitro through cell cycle arrest and apoptosis,11 and targets c-MYC oncogene to prevent PCa growth in vitro and in vivo.