Warfarin may produce one surprising benefit: protection against cancer. Researchers from Norway studied this issue in a population cohort of more than 1.25 million persons. The cohort was divided into warfarin users and nonusers. Warfarin users were divided into those taking it for AF or other reasons. To be counted in the cohort, warfarin had to be taken for six consecutive months. Those taking warfarin were older and predominately men. The results showed that warfarin users demonstrated significantly lower age- and sex-adjusted incidences of cancer in all sites (incidence rate ratio [IRR], 0.84; 95% CI, 0.82-0.86). In warfarin users, the IRR for the most common cancers compared to nonusers were: 0.80 lung cancer, 0.69 prostate cancer, and 0.90 breast cancer. However, warfarin did not lower the incidence of colon cancer. Those taking warfarin for AF exhibited even lower rates of cancer. The finding that warfarin lowers the risk of cancer is plausible because warfarin inhibits AXL receptor tyrosine kinase-dependent tumorigenesis and enhances antitumor immune responses, even at doses below anticoagulation levels. The authors suggested that “warfarin use may have broad anticancer potential in a large, population-based cohort of persons older than 50 years.” This finding may have implications for selection of an anticoagulant for certain patients (JAMA Intern Med 2017 Nov 6. doi: 10.1001/jamainternmed.2017.5512).