Regular Aspirin Use May Reduce Colorectal Cancer Risk, Study Suggests

The benefit was greatest for people who smoke cigarettes, have higher body mass indexes, or have other lifestyle-related risk factors for the disease.

Boxes of aspirin tablets on a store shelf in Miami on April 12, 2016. Illustration by Joe Raedle/Getty Images

Regular aspirin use may reduce the chance of developing colorectal cancer in individuals who are at a higher risk of developing the cancer.

Published in the JAMA Oncology journal on Aug. 1, a study found that weekly aspirin usage could lower the risk of developing the cancer in individuals who smoked cigarettes, had higher body mass indexes, or other lifestyle-related risk factors for the disease.

That group had a 3.4 percent chance of getting colorectal cancer, which impacts the colon or rectum, if they did not take aspirin on a weekly basis. Individuals who take aspirin regularly had a 2.12 chance of developing the cancer, researchers found.

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There was little difference among people who were deemed to have healthier lifestyles. If they took aspirin on a regular basis, they had a 1.5 percent chance of developing colorectal cancer. If they did not, they had a 1.6 percent chance of developing the cancer, according to the study.

The group defined regular usage as two or more 325 mg pills, or at least six 81 mg pills, per week. The study also evaluated 108,000 men and women who had an average age of 49 years for three decades and recorded their aspirin intake, and gave them scores based on their cigarette usage, alcohol consumption, body mass index, diet, and other factors.

Researchers obtained the data from large datasets known as the Health Professionals Follow-Up Study and the Nurses’ Health Study.

“Our results show that aspirin can proportionally lower the markedly elevated risk in those with multiple risk factors for colorectal cancer,” Daniel Sikavi, the paper’s lead author who is a gastroenterologist with the Mass General Cancer Center, said in a news release.

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“In contrast, those with a healthier lifestyle have a lower baseline risk of colorectal cancer, and, therefore, their benefit from aspirin was still evident, albeit less pronounced.”

Authors of the study cautioned that their paper did not make any determinations about the potential side effects of regular aspirin usage, including internal bleeding.

“In addition, while the study tried to control for a wide range of risk factors for colorectal cancer, in comparing non-aspirin and aspirin-taking groups with the same level of risk factors, because this was an observational study, it is possible there may have been additional factors that influenced the findings,” the release said.

The National Cancer Institute says that colorectal cancer is the second-leading cause of cancer-related death in the United States, behind lung cancer. The American Cancer Society has estimated that around 46,220 cases of rectal cancer and 106,590 new cases of colon cancer will be diagnosed in the United States in 2024. Colorectal cancer is expected to cause about 53,010 deaths this year.

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The American Cancer Society has noted that deaths from colorectal cancer have been waning among older adults in recent decades. Advances in screening have allowed doctors to remove potentially cancerous growths known as polyps before they can develop further.

For decades, a daily aspirin dose of 81 milligrams was recommended by heart associations and physicians to reduce the chance of developing a heart attack or stroke. However, in 2019, the American College of Cardiology and the American Heart Association changed their guidelines and said that only people who have a high risk of stroke or a heart attack should continue with a daily 81-milligram dose.

Aspirin can irritate the lining of the stomach, triggering internal bleeding, ulcers, and gastrointestinal problems. A blood thinner, aspirin can be dangerous for individuals who are at a high risk of bleeding.

People who use aspirin and another blood thinner can also run the risk of developing adverse reactions. Common blood thinners include other non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen as well as heart drugs like warfarin.

Some common herbal supplements such as turmeric, garlic, and ginger also thin the blood.

In April, a study published in the Journal of the American Cancer Society also found that taking daily, low-dose aspirin could reduce the death rates and development of colorectal cancer.