Daily aspirin to prevent colorectal cancer
Conflicting evidence, real bleeding risks, and a warning sign in people 70 and older.
What studies found
The National Cancer Institute says daily aspirin taken for at least two years lowers colorectal cancer risk and deaths, but the drop begins only 10 to 20 years after starting. In 2022 the U.S. Task Force judged the evidence inadequate to show that low-dose aspirin lowers colorectal cancer cases or deaths. In the ASPREE trial of about 19,000 adults 70 and older, daily aspirin was linked to more deaths from colorectal cancer.
The catch
The ASPREE result was unexpected and needs confirmation. This entry is about prevention in people without cancer; aspirin after surgery for PI3K-altered colorectal tumors is a separate entry.
What to do
Don't start daily aspirin to prevent cancer on your own, especially at 70 or older. If you already take aspirin for a medical reason, don't stop without talking to your doctor.
Sources
Rung 2 of 5, Limited: Few, small or conflicting human studies, or only indirect measures such as blood markers. How we score
Step by step
For the whole picture, from prevention and screening to treatment and life after, see the colorectal cancer page.
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