Research suggests that taking a small dose of daily aspirin over a period of years can reduce the risk of certain cancers. The strongest data favoring aspirin as a preventive are for cancers of the colon and rectum, stomach, and esophagus.
In April 2016, the U.S. Preventive Services Task Force released a recommendation stating that a low-dose aspirin regimen is most beneficial for adults age 50-59.
“Our research has demonstrated a benefit for aspirin in reducing the risk of colorectal cancer, and we are pleased with the new recommendations from the U.S. Preventive Services Task Force,” says Charles S. Fuchs, MD, MPH, former director of the Gastrointestinal Cancer Center at Dana-Farber, said in 2016. “Our ongoing research seeks to fully understand the mechanisms by which aspirin reduces the risk of colorectal cancer and assess whether we can leverage those findings to improve the treatment of patients with established colorectal cancer.”
According to the Task Force recommendations, the adults most likely to benefit from aspirin are those who are not at risk for gastrointestinal bleeding, have a life expectancy of at least 10 years, and who are willing to take low-dose aspirin daily for at least 10 years.
For adults age 60-69, the Task Force recommends individuals speak with their primary care physician about the risks and benefits of aspirin use, and whether a low-dose regimen is right for them. The Task Force’s findings did not have sufficient evidence showing an aspirin regimen would be beneficial for adults younger than 50 or older than 70.
The biggest obstacle to recommending routine aspirin use is the significant risk of causing gastrointestinal bleeding, which can be fatal. So, it is important to weigh the risks and benefits with a physician.
Data supporting an aspirin regimen
In August 2014, researchers from London’s Queen Mary University concluded that daily aspirin taken over 10 years reduced the risk of developing cancers of the digestive tract – colon, stomach, and esophagus – by as much as 40 percent, and had a lesser impact on the number of lung, breast and prostate cancer diagnoses. The leader of the research – published in the Annals of Oncology, said “the evidence is that everyone between 50 and 65 should consider [taking daily] aspirin.”
A team at Fox Chase Cancer Center in Philadelphia has also presented research showing that low-dose aspirin helps suppress inflammatory pathways that feed prostate cancer cell formation. And another study in 2014 reported that daily aspirin could reduce the risk of ovarian cancer by 20 to 34 percent.
However, it is important to consider that many of these aspirin studies are observational and designed to look for preventive effects in heart disease, rather than side-by-side comparisons of aspirin versus no aspirin for cancer prevention.
More research is needed
A 2010 review of four clinical trials revealed that over a 20-year period, taking low doses of aspirin was associated with a 24 percent reduction in colon cancer cases and a 35 percent drop in deaths.
However, a study by researchers at Dana-Farber and Massachusetts General Hospital has suggested that this benefit may be limited to individuals who are already at high risk of colon cancer because they have elevated levels of an inflammatory factor called TNFR-2in their blood. Fuchs, senior author of the study, noted that TNFR-2 was the only one of three inflammatory markers that was relevant to colon cancer risk, showing that testing for specific biomarkers likely will be needed to identify patients who might benefit from preventive use of aspirin or other anti-inflammatory drugs.
This finding reflects a larger set of unanswered questions about aspirin as a cancer preventive: Who might benefit – people who are at low risk for developing cancer, or those at high risk? How long does it take for aspirin’s presumed protective effect to kick in, and how long must the drug be taken for maximum benefit?
Research continues. Meanwhile, patients should discuss the pros and cons of daily aspirin, as with any course of medication, with their doctor.
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Ed. note: This post was originally published in October 2014 and updated in April 2016.