Can metformin prevent cancer?

Short Answer: Epidemiological studies consistently show 20-40% lower cancer incidence in diabetic patients taking metformin. The TAME trial is testing metformin for age-related disease prevention including cancer.

Evidence Level: moderate

Detailed Answer

Multiple meta-analyses encompassing millions of diabetic patients show that metformin use is associated with a 20-40% reduction in cancer incidence across breast, colorectal, prostate, and pancreatic cancers compared to other diabetes medications. Proposed mechanisms include AMPK activation (suppressing mTOR-driven cell growth), reduced circulating insulin/IGF-1 levels, inhibition of mitochondrial Complex I, and anti-inflammatory effects. The landmark TAME trial (Targeting Aging with Metformin, NCT02432287) is testing metformin 1500mg/day in 3,000 non-diabetic adults aged 65-79 to determine if it delays age-related diseases including cancer. Early results are expected by 2027. Metformin is one of the safest drugs ever produced, with over 60 years of clinical use.

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