Aspirin Falls Short for Colorectal Cancer Prevention, New Review Finds — Try These Lifestyle Changes Instead

A large-scale analysis of past research suggests that taking a daily low-dose aspirin probably won’t lower your chances of getting colorectal cancer, and it may raise the risk of bleeding in and around the brain.

Researchers found that daily aspirin use likely does not help prevent colorectal cancer during the first 15 years of use. It might offer some protective benefits after that point, but the scientists said they are “not confident” in that long-term finding.

The review also showed that daily aspirin might increase deaths from colorectal cancer in the short term. However, after 15 years, it could possibly reduce deaths — again, the researchers noted they are “not confident” in this conclusion.

On the safety side, the analysis confirmed that daily aspirin can increase the risk of serious bleeding outside the skull as well as bleeding in the brain area.

“It is not possible to draw definitive conclusions or outline specific implications for the routine use of aspirin for [colorectal cancer] primary prevention based on the current evidence,” the researchers wrote. They described their findings as showing “complex, time‐dependent preventive effects and concerns about potential harms for clinicians and patients to consider.”

The study was published April 1 in the Cochrane Database of Systematic Reviews. It updates a previous report the same team released in February.

Dr. Ketan Thanki, a colorectal surgeon at the MemorialCare Todd Cancer Institute in California, said the new report offers a word of caution. “This study demonstrates limited (if any) protective benefit from aspirin on risk of developing colorectal cancer in the general population,” he said. “With the known potential complications of long-term aspirin use, I would recommend that people don’t take daily aspirin solely with the intent of reducing your risk of developing colorectal cancer.”

What the Research Found

To reach these conclusions, researchers looked at data from 10 randomized controlled clinical trials. They compared aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) with no treatment or a different treatment for preventing colorectal cancer or precancerous growths called adenomas.

The studies involved more than 120,000 participants, mostly from North America and Europe. Most people took low-dose aspirin (75 to 100 mg per day), though three studies tested higher doses.

The researchers determined that daily aspirin “probably results in little to no difference” in colorectal cancer risk after 5 to 15 years of use. After 15 years, aspirin might slightly lower risk, but the evidence was not strong enough to be certain.

Thanki noted that daily aspirin might still be helpful for certain high-risk groups. “I would advise that you only consider daily aspirin for this purpose, either if you have a genetic syndrome that predisposes you to cancer (specifically Lynch Syndrome) or have had adenomatous polyps removed during a prior colonoscopy,” he said. He pointed to good evidence that aspirin can lower cancer risk in people with Lynch Syndrome and reduce the chance of polyps returning. He urged those patients to talk with their doctors.

The researchers also reported that daily aspirin “may increase mortality” from colorectal cancer between 5 and 10 years of use. Between 10 and 15 years, it made “little to no difference,” and after 15 years, there was a possible reduction in deaths.

When it came to colorectal adenomas (precancerous polyps), aspirin “may result in little to no difference” between 5 and 10 years, but the evidence was “very uncertain.”

Overall, daily aspirin made “little to no difference” in total serious side effects. However, the researchers confirmed that aspirin “does increase the risk of serious extracranial hemorrhage” and “probably increases the risk of hemorrhagic stroke.”

“The uncertain and delayed potential for benefit must be weighed against a definite harm,” the researchers wrote. They added that doctors should continue to make individual decisions with their patients, balancing heart disease risk against bleeding risk.

Mixed Messages from Past Studies

The new review adds to a confusing body of research. An August 2024 study found that regular aspirin use could lower colorectal cancer risk, especially in people who are obese or have unhealthy habits like smoking. An April 2024 study also suggested daily aspirin might offer some protection, possibly by helping the immune system spot cancer cells.

But a January 2026 study reported that daily aspirin did not seem to reduce cancer in older adults and might actually increase the risk of dying from cancer in that age group.

This conflicting evidence has led to changes in official advice. In 2016, the U.S. Preventive Services Task Force (USPSTF) recommended low-dose aspirin for colorectal cancer prevention in adults ages 50 to 59. But in 2022, the task force withdrew that recommendation, saying there wasn’t enough proof that daily aspirin lowers the risk of getting or dying from colorectal cancer.

Experts agree that anyone considering daily aspirin should talk to their doctor first. “Daily low dose aspirin use can decrease risk of cardiovascular disease such as coronary artery disease, heart attacks, and strokes,” Thanki said. “It may decrease the risk of preeclampsia in high risk pregnancies, and, as we discussed, polyps and tumors in the colon. It is important to know that this is highly nuanced and you should always talk with your doctor to see if daily aspirin use is right for you.”

Dr. Katherine Van Loon, a gastrointestinal cancer specialist at the University of California San Francisco, noted that age matters. “Age of aspirin initiation also seems to play a role and younger patients may benefit more,” she said in an earlier interview. “For now, I think we can say that we shouldn’t initiate aspirin therapy in an older adult for the sole purpose of cancer prevention.”

Better Ways to Lower Your Risk

Experts say there are proven lifestyle habits that can help reduce your risk of colorectal cancer. These include:

– Eating more plant-based foods

– Eating less red meat and processed meat

– Limiting alcohol

– Quitting smoking

– Keeping a healthy weight

– Exercising daily

Thanki emphasized a diet high in fiber and low in red meat, processed meat, sugar, and alcohol. “A lifestyle of moderation is most important in reducing your risk of colorectal cancer,” he said. “Diet and exercise are the best and easiest ways you can decrease your cancer risk.”

He also stressed the importance of screenings. “Colonoscopy is the best way to prevent and detect cancer, but other options like Cologuard are also now available.”

Van Loon agreed. “We recommend avoiding tobacco use, maintaining a healthy weight, exercising, and consuming a diet that is low in red meat, processed meats, sugar, and ultra-processed foods,” she said. “In addition, participation in routine age-appropriate cancer screening is important.”