Warfarin is a medication used to reduce the risk of heart attack or stroke. A new study, however, suggests that the drug may also help to reduce the risk of cancer, particularly for people aged 50 and older.
Study co-author James B. Lorens, Ph.D., of the University of Bergen in Norway, and colleagues recently reported their findings in JAMA Internal Medicine.
Warfarin is a type of anticoagulant, or blood thinner, that helps to prevent the formation of blood clots. It works by inhibiting the body's production of vitamin K, which is needed to form blood clots.
The medication is most commonly prescribed to people who have experienced heart attack, stroke, deep vein thrombosis, and other conditions caused by blood clots. Warfarin may also be prescribed for people at increased risk of developing blood clots, including individuals with arrhythmia, or irregular heartbeat, and those with prosthetic heart valves.
Specifically, studies in cancer models have shown that warfarin blocks AXL receptor tyrosine kinase by inhibiting a vitamin K-dependent protein called Gas6, which may halt the spread of cancer cells.
For this latest study, Dr. Lorens and colleagues set out to determine whether or not warfarin use might reduce the risk of cancer development.
Cancer risk reduced by 16 percent
For their study, the researchers used data from the Norwegian National Registry, the Norwegian Prescription Database, and the Cancer Registry of Norway.
The team included data on 1,256,725 individuals who were born in Norway between January 1924 and December 1954, of whom more than half were female.
They collected information on participants' warfarin use from January 2004 to December 2012, and cancer incidence among the subjects was assessed from January 2006 to December 2012. Of the study participants, 92,942 were taking warfarin.
The researchers found that individuals who used warfarin had a 16 percent reduced risk of all cancers, compared with people who did not use the drug.
Additionally, the researchers assessed how warfarin use influenced the risk of cancer development in a subgroup of individuals who were prescribed the drug for atrial fibrillation or atrial flutter.
Results revealed that these individuals were at lower risk of cancer development overall, and they were also less likely to develop prostate, lung, breast, and colon cancers.
Warfarin offers 'possible cancer protection'
Taken together, Dr. Lorens and team believe that their findings suggest that warfarin may help to prevent cancer. They write:
"Our data indicate that warfarin provides a possible cancer protection, a finding that may have important implications for choosing medications for patients who need anticoagulation."
That said, the team notes that their study is observational, so they are unable to prove cause and effect.
There are also a number of study limitations to consider. For example, the researchers did not gather data on participants' use of other medications, nor did they account for other factors that might influence the risk of cancer development, such as their diet, weight, and smoking status.
The team concludes that further studies are needed to determine the underlying mechanisms by which warfarin may protect against cancer development.