The fact that C75's ability to prevent mammary carcinomas via blockade of FASN-regulated lipogenesis appears to recapitulate metformin's cancer preventive effects in neu-N female mice suggests that metformin may have tumor suppressing and/or lifespan prolonging effects in response to specific metabolic phenotypes (e.g. high fuel intake, metabolic syndrome, diabetes and/or increased activation of oncogenic signals having similar effects on energy metabolism) but may have little or no effect at controlling cancer processes driven by energy-independent molecular events. The gene discussed is FASN; the disease is cancer.