Inactivation of the GH/insulin/IGF-1 signaling molecules corresponding genes as well as the inactivation of serine/threonine protein kinase mTOR increases life span in nematodes, fruit flies and mice. Evidence has emerged that antidiabetic biguanides and rapamycin are promising candidates for pharmacological interventions leading to both life span extension and prevention of cancer. The available data on the relationship of two fundamental processes--aging and carcinogenesis--have been suggested to be a basis for understanding these two-side effects of biguanides and rapamycin.