Taking aspirin regularly may reduce the risk of most types of colon cancer, a new study suggests.
In the study, people who took aspirin at least twice a week were 27 percent less likely to develop colon cancer over a 28-year period, compared with those who took aspirin less frequently, or not at all.
However, this reduction in risk applied only to colon cancers that did not have a mutation in a gene called BRAF. Taking aspirin regularly did not reduce the risk of developing colon cancer with a BRAF mutation; about 10 to 15 percent of colon cancers have this mutation.
The findings agree with previous research showing a reduced risk of colon cancer among people who take regular aspirin. But the new results suggest that colon cancers with a BRAF mutation may be less sensitive to the effects of aspirin, the researchers said.
The next key question is to determine which people are more likely to develop BRAF-mutated colon cancer, said study researcher Dr. Andrew T. Chan, a gastroenterologist at Massachusetts General Hospital. People at risk for this specific colon cancer may not benefit from regularly taking aspirin, Chan said. [See 5 Interesting Facts About Aspirin].
Because the study included mainly white participants, the findings should be confirmed in a more diverse population, the researchers said.
Despite growing evidence linking regular aspirin use with a reduced risk of cancer, the drug is not generally recommended as a way to prevent cancer. Taking aspirin comes with risks, including an increased risk of gastrointestinal bleeding, and so researchers need to figure out what groups would be most likely to benefit from such a recommendation.
People interested in taking regular aspirin should speak with their doctor first, Chan said.
The study included more than 127,000 people who were followed from the 1980s until 2012. During this time, 1,226 people in the study developed colon cancer.
The rate of non-BRAF mutated cancer was 40.2 cases per 100,000 people per year among those who did not regularly take aspirin, but only 30.5 cases per 100,000 people per year among those who regularly took aspirin.
The rate of BRAF-mutated cancer was 5 cases per 100,000 people per year among those who did not regularly take aspirin and 5.7 cases per 100,000 people per year among those who took regular aspirin, a difference that may have been due to chance.
Taking aspirin more frequently was linked with a lower risk of non-BRAF mutated cancer, but not BRAF-mutated cancer. Those who took six to 12 doses of aspirin weekly were 30 percent less likely to develop non-BRAF mutated cancer than those who did not take aspirin, the study said.
For people who had been diagnosed with colon cancer, taking aspirin did not affect patient survival, regardless of cancer type, the study also found.
The study is published in the June 26 issue of the Journal of the American Medical Association. It was funded by National Institutes of Health (NIH); the Bennett Family Fund for Targeted Therapies Research; and the National Colorectal Cancer Research Alliance. Chan has previously worked as a consultant for Bayer Healthcare, which manufactures aspirin.
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Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.