Aspirin and Colorectal Cancer: Drug Could Lower Risk for Those with Unhealthy Lifestyles

A tool for preventing colorectal cancer (CRC) may already be in your medicine cabinet—new research found taking aspirin on a regular basis could help reduce the risk of colorectal cancer, especially for those with less healthy lifestyles.

The large-scale cohort study, published in JAMA Oncology on August 1, analyzed more than 30 years’ worth of data from more than 107,000 participants. The results showed that people with a less-healthy lifestyle saw a greater reduction of CRC risk than those engaging in healthier behaviors. This lowered CRC risk was especially pronounced in people who smoked and had higher body mass indexes (BMIs).¹

The study’s findings are especially interesting given reports of rising CRC rates, especially among younger generations.

“The increase in early-onset colorectal cancer—colorectal cancer diagnosed before age 50—is a particularly disturbing trend,” Tingting Tan, MD, PhD, medical oncologist and hematologist at City of Hope Newport Beach, told Health. “By 2030, colorectal cancer is projected to be the leading cause of cancer deaths for young adults in the U.S. We urgently need to address this problem through research, education, and better screening.”²

Here’s what to know about the new research and what we know about the use of an aspirin regimen to prevent CRC.

Lifestyle, Aspirin Use, and Colorectal Cancer Risk

Previous research has shown a link between a person’s lifestyle habits—such as smoking and alcohol consumption—and their risk of CRC.³⁴⁵ In order to determine whether taking aspirin might be a useful preventative strategy against CRC, the authors of this new study took lifestyle factors into account when analyzing their data.

Data from a total of 107,655 participants were used in the study, including 63,957 women from the Nurses’ Health Study and 43,698 men from the Health Professionals Follow-Up Study. The average age was 49.¹

The study authors defined a “less healthy lifestyle” using five of the most well-established and modifiable risk factors for CRC: a higher BMI, greater smoking history, higher alcohol consumption, less physical activity, and a poorer quality diet.¹

“All five factors have been linked to inflammatory processes linked to long-term cancer outcomes,” study authors Andrew Chan, MD, MPH, and Long Nguyen, MD, told Health in a joint statement.

At Massachusetts General Hospital, Chan is the director of epidemiology for the Cancer Center and gastroenterology director of the Center for Young Adult Colorectal Cancer, and Nguyen is a physician investigator and assistant professor of medicine and gastroenterology.

The study’s participants filled out questionnaires answering questions about their height, weight, diet, physical activity, and smoking habits. Participants were then given a lifestyle score ranging from zero (unhealthiest) to five (healthiest).¹

After analyzing CRC incidence over the course of about 30 years, Chan and Nguyen found that people who used aspirin regularly (taking two or more standard tablets weekly) had an 18% lower risk of developing CRC as compared to non-aspirin users.¹

This lower risk was stratified based on people’s lifestyle scores, with people scoring a zero or one seeing a greater reduction in CRC risk. However, the over-the-counter drug can benefit those with healthier habits, too.

“Though we observed that participants in our study with the least healthy lifestyle had the greatest absolute benefit from aspirin use, we also show that those with a healthier lifestyle who have a lower baseline risk of colorectal cancer may still benefit from aspirin,” Chan and Nguyen said.

 Study: Daily Aspirin May Help Boost the Immune System and Prevent Spread of Colorectal Cancer

Why Might Aspirin Reduce Colorectal Cancer Risk? 

This study is not the first to suggest a link between aspirin use and a lowered colorectal cancer risk.

“For centuries, aspirin has been praised for its healing capabilities as an anti-inflammatory and a pain reliever,” Tan explained.⁶

More specifically, “aspirin and other non-steroidal anti-inflammatory drugs…are believed to reduce colon cancer risk by inhibiting the production of proinflammatory proteins known as prostaglandins,” Thomas Deas, MD, a gastroenterologist at Texas Health Harris Methodist Hospital and associate professor at the Texas Christian University Burnett School of Medicine, told Health.

Essentially, the theory is that long-term aspirin use can reduce this inflammation that might otherwise lead to cancer.⁷

Aspirin might also block the development of blood vessels that supply nutrients to growing cancers and “influence the immune response against cancer cells,” Chan and Nguyen added.

Multiple studies have indicated that an aspirin regimen may help prevent polyps in the colon and rectum from developing or recurring, therefore reducing a person’s chance of developing cancer, Tan said. The over-the-counter drug might assist in curbing the production of a protein that controls cell growth and division.⁸

Additionally, a 2016 study found that long-term aspirin use was linked to a lower risk for overall cancer—specifically gastrointestinal tract tumors—while a 2020 study found that aspirin appeared to reduce tumor growth and inhibit the recurrence of CRC.⁹

In the past, the U.S. Preventive Services Task Force recommended that most adults ages 50 to 59 take low-dose aspirin daily to prevent colorectal cancer. However, the organization has since withdrawn that recommendation due in part to concerns about aspirin increasing the risk of gastrointestinal bleeding, as well as the need for more research.¹⁰

This possible connection between aspirin and bleeding was a limitation in Chan and Nguyen’s study, they said.

“[The study] did not systematically assess potential side effects associated with aspirin use that might otherwise prevent its long-term use,” they explained. In other words, there isn’t data about the number of people who take aspirin regularly and who have complications such as bleeding, Tan pointed out.

“While these findings appear promising, future studies are needed to validate the findings,” she said.

Should You Take Low-Dose Aspirin Daily? Experts Weigh Pros and Cons

Talk to Your Doctor Before Starting an Aspirin Regimen 

Despite the study’s positive results, it’s too soon to say whether people should start an aspirin regimen to prevent CRC, Deas said.

“It may well be that the inhibition of inflammatory agents in the colon will prove both safe and successful in reducing colon cancer risk,” he said, though more research needs to be done.

“Patients should discuss their relative risk and benefit with their physician who knows them best,” Deas added.¹⁰

If you’re already taking aspirin under physician supervision, including for prevention of another cardiovascular event, “you may also be decreasing your risk of colorectal cancer,” Tan said. If you’re not currently on an aspirin regimen, talk to your doctor before taking it or any other medication, she said.¹⁰

Whether aspirin is right for you, the most important thing you can do to reduce your risk of CRC is to adopt a healthy lifestyle, Tan said. This includes maintaining a healthy weight, eating plenty of fruits, vegetables, grains, and lean proteins, getting quality sleep, exercising, and avoiding tobacco and alcohol, she advised.

“This study provides further evidence that making healthy lifestyle choices is one the best ways to reduce the risk of developing cancer, including colon cancer and more,” she said. “It’s also important for everyone to get their recommended screenings, including colonoscopy.”