Aspirin has many uses, from easing a headache or cooling a fever to preventing heart attacks and the most common kind of stroke. It may be time to add “preventing colorectal cancer” to the list. New results from the Women’s Health Study, a clinical trial that evaluated the benefits and risks of low-dose aspirin and vitamin E among nearly 40,000 women, show that aspirin reduces the risk of developing colorectal cancer by 20%. The effect isn’t immediate, but instead takes ten to 20 years to be seen. Aspirin isn’t without its drawbacks, including gastrointestinal bleeding and ulcer formation. Both occurred slightly more often among women taking aspirin. Although the Women’s Health Study results sound promising, don’t go reaching for the aspirin bottle just yet. Taking aspirin—and any other drug—is really a balancing act between benefits and risks.
Back in 2009, Dr. Andrew T. Chan and his colleagues at Harvard-affiliated Massachusetts General Hospital found that people diagnosed with colorectal cancer who took aspirin on a regular basis tended to live longer than those who didn’t take aspirin. Aspirin worked only for some people, though, so Chan and a larger team of researchers set out to learn why. Their latest work, published in the New England Journal of Medicine, indicates that people with colorectal cancer who have a mutation in a gene called PIK3CA are most likely to benefit from aspirin. (About 15% to 20% of people with colorectal cancer have this gene mutation.) The mutation permits colon cancer cells to thrive. Aspirin blocks this action. If confirmed, this work could lead to routine genetic testing for people with this common cancer, and aspirin therapy for those with the PIK3CA mutation.