Warfarin May Reduce Risk of Cancer

A widely-used anticoagulant may have protective benefits for cancer, according to a study published in JAMA Internal Medicine.

In the study, the researchers investigated the association between warfarin use and cancer incidence to determine whether warfarin has anticancer potential. The study, which was a population-based cohort study with subgroup analysis, used data from the Norwegian National Registry, Norwegian Prescription Database, and Cancer Registry of Norway. The cohort was divided into 2 groups of warfarin users and nonusers, with the subgroup being individuals taking warfarin for atrial fibrillation.

Warfarin use in the study was defined as taking at least 6 months of a prescription and at least 2 years from first prescription to any cancer diagnosis.

Of the 1,256,725 participants in the cohort, which included everyone living in Norway between Jan. 1, 2006 and Dec. 31, 2012, and who were born between Jan. 1, 1924 and Dec. 31, 1954, nearly 11% had cancer, 7.4% were classified as warfarin users, and 92.6% were classified was nonusers. Most of the warfarin users were predominantly older men.

The researchers noted that warfarin users had a 16% reduced risk of all cancers, compared with nonusers. Use was linked with a 31% reduced risk of prostate cancer, 20% reduced risk of lung cancer, and a 10% lower risk of breast cancer. In the subgroup, individuals who used warfarin were at a lower risk of cancer overall, and were less likely to develop prostate, lung, breast, and colon cancers.

In cancer models, warfarin inhibits GAS6-AXL signaling and blocks tumorigenesis, which suppresses antitumor immunity, according to the study. The researchers noted that the observed association between warfarin use and lower cancer incidence is likely due in part to an enhanced antitumor immune surveillance of early cancer.

Overall, the researchers concluded that their findings may have important implications for choosing medications for patients who need anticoagulation. Although the data point to possible cancer protection, further studies are needed to fully clarify these observations.

Reference

Haaland GS, Falk RS, Straume O, et al. Association of warfarin use with lower overall cancer incidence among patients older than 50 years. JAMA Intern Med. 2017; doi:10.1001/jamainternmed.2017.5512.