Metformin,a biguanide derivate,has been in use as an anti-diabetic agent for over 60 years and has been widely accepted as first-line therapy for the management of type Ⅱ diabetes.Interestingly,the treatment of type Ⅱ diabetes with metformin is associated with reduced risk and improved prognosis for many types of cancers[1].This observation has led to an explosion of interest in the potential application of metformin for cancer chemopreventive and direct antitumor effects,but also more recently for potential immunomodulatory activity.
