In conclusion, since beneficial effects of metformin are not seen in all cancers further studies are required to determine whether the anti-cancer actions are direct or are secondary to the positive effects of metformin on healthspan that are apparent in obese patients such as improved glucose homeostasis, enhanced insulin sensitivity and reduced signaling through the IGF-1–mTOR pathway (114, 242), Table 2. The gene discussed is MTOR; the disease is cancer.