March 24, 2025—A recent study found that taking aspirin every day may help prevent colorectal cancer from recurring. That adds to research indicating aspirin might help prevent colorectal cancer from developing or spreading. But it doesn't mean a daily aspirin is a good idea for everyone.
What the science says
A study presented at the 2025 American Society of Clinical Oncology Gastrointestinal Cancers Symposium looked at whether aspirin could keep colorectal cancer from coming back. Researchers followed 626 patients in Denmark, Finland, Norway and Sweden. All the patients had colorectal cancer with a genetic mutation known as PI3K. PI3K occurs in about 30% of colorectal cancers. It can appear in other cancers too. Some patients took a low dose (160 milligrams) of aspirin daily. Others took a placebo.
Researchers followed the participants for three years. They learned that a recurrence of colorectal cancer was 55% less likely in the patients who took the daily dose of aspirin compared to the patients who didn't.
Another study found that colorectal cancer patients who had been taking aspirin regularly before their diagnosis were less likely to die than the patients who hadn't been taking aspirin. The aspirin-takers were also less likely to have their cancer spread.
Taking aspirin after being diagnosed didn't seem to raise or lower the patients' risk of cancer death.
Other studies have noted a connection between aspirin use and a lower risk of colorectal cancer and polyps, says the American Cancer Society. But that protection may take time—at least five years of use, according to UpToDate.
Other benefits—and risks
Scientists don't have all the answers yet on the possible link between aspirin and colorectal cancer prevention. Aspirin lowers inflammation, which could be a factor.
Aspirin is a common treatment for people at higher risk for stroke or heart attack. It makes your blood thinner. This reduces the formation of dangerous blood clots in vessels leading to your heart and brain.
Aspirin isn't risk-free, however. The side effects of regular use include:
- Increased bleeding risk. This is especially true for older adults and people who take another type of pain reliever or blood-thinning medication.
- Stomach and small intestine inflammation. Inflammation could cause ulcers and bleeding.
- An allergic reaction. People with an aspirin allergy can have a reaction ranging from mild to severe.
For many people, the possible benefits of daily aspirin don't outweigh these risks.
The bottom line: Don't start taking aspirin regularly without talking with your doctor first. Ask them if it's right for you.
Dig deeper
See if you know what does or doesn't help prevent cancer.
Sources
- American Cancer Society. "Can Aspirin Help Reduce Your Cancer Risk?" https://www.cancer.org/cancer/latest-news/can-aspirin-help-reduce-your-cancer-risk.html.
- American Cancer Society. "Does Regular Use of Aspirin Improve Colorectal Cancer Survival?" https://www.cancer.org/research/acs-research-highlights/colon-and-rectal-cancer-research-highlights/survivorship-colorectal-cancer-studies/regular-use-of-aspirin-may-help-improve-survival-after-a-diagnos.html.
- American Heart Association. "Aspirin and Dual Antiplatelet Therapy." https://www.heart.org/en/health-topics/heart-attack/treatment-of-a-heart-attack/aspirin-and-heart-disease.
- American Society of Clinical Oncology. "Aspirin May Reduce Risk of Colorectal Cancer Recurrence for Some Patients." https://www.asco.org/about-asco/press-center/news-releases/new-findings-aspirin-and-risk-colorectal-cancer-recurrence.
- UpToDate. "Patient Education: Aspirin in the Primary Prevention of Cardiovascular Disease and Cancer (Beyond the Basics)." https://www.uptodate.com/contents/aspirin-in-the-primary-prevention-of-cardiovascular-disease-and-cancer-beyond-the-basics/print.