A colorectal cancer (CRC) prevention tool may already be in your medicine cabinet: A new study finds that taking an aspirin regularly may help reduce the risk of colorectal cancer, especially in people with less-than-healthy lifestyle habits.
A large cohort study published August 1 in JAMA Oncology analyzed more than 30 years of data from more than 107,000 participants and found that people with unhealthy lifestyles had a greater reduction in colorectal cancer risk than those with healthy behaviors. This reduction in colorectal cancer risk was especially pronounced in smokers and those with a high body mass index (BMI).
The findings are particularly interesting given reports of rising incidence of colorectal cancer, especially among younger generations.
“The increase in colorectal cancer diagnosed under age 50 — early-onset colorectal cancer — is a particularly alarming trend,” Ting-Ting Tan, MD, PhD, a 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 death among young adults in the United States. We urgently need to address this issue through research, education, and improved screening.”
Here's what you need to know about the new research and what we know about the use of aspirin therapy to prevent CRC.
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Previous studies have shown that lifestyle habits such as smoking and drinking alcohol are associated with the risk of developing colorectal cancer. To determine whether taking aspirin is effective in preventing colorectal cancer, the authors of the new study took lifestyle factors into account when analyzing the data.
The study used data from a total of 107,655 participants, 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 years.
The study authors defined an “unhealthy lifestyle” using the five most established and modifiable risk factors for CRC: high BMI, high smoking history, high alcohol intake, low physical activity, and poor diet.
“All five factors are linked to inflammatory processes that lead 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 serves as director of epidemiology in the Cancer Center and director of gastroenterology in the Young Adult Colorectal Cancer Center, and Nguyen is a physician-investigator and assistant professor of medicine and gastroenterology.
Study participants filled out questionnaires about their height, weight, diet, physical activity and smoking habits. They were given a lifestyle score ranging from 0 (least healthy) to 5 (most healthy).
After analyzing CRC incidence rates over a period of nearly 30 years, Trang and Nguyen found that people who took aspirin regularly (two or more standard tablets per week) had an 18% lower risk of developing CRC compared with people who did not take aspirin.
This risk reduction is stratified based on people's lifestyle score, with people with a score of 0 or 1 seeing a greater reduction in CRC risk, but this over-the-counter drug could also benefit people with healthy habits.
“In our study, we observed that participants with the unhealthiest lifestyles derive the greatest absolute benefit from aspirin use, but our study also indicates that participants with healthier lifestyles who have a lower baseline risk of colorectal cancer may also benefit from aspirin,” said Chan and Nguyen.
This study is not the first to suggest a link between aspirin use and a reduced risk of colorectal cancer.
“For centuries, aspirin has been prized for its healing properties as an anti-inflammatory and pain reliever,” Tan explained.
More specifically, “aspirin and other nonsteroidal anti-inflammatory drugs are thought to reduce the risk of colorectal cancer by inhibiting the production of pro-inflammatory proteins known as prostaglandins,” Thomas Deas, MD, a gastroenterologist at Texas Health Harris Methodist Hospital and associate professor at Texas Christian University Burnet College of Medicine, told Health.
Essentially, the theory is that long-term use of aspirin can reduce inflammation that can lead to cancer.
Aspirin may also inhibit the development of blood vessels that supply nutrients to growing cancers and “affect the immune response to cancer cells,” Trang and Nguyen added.
Studies have shown that aspirin therapy may help prevent the development and recurrence of polyps in the colon and rectum, and therefore reduce the risk of developing cancer, Tan said. The over-the-counter drug may help inhibit the production of proteins that control cell growth and division.
Additionally, a 2016 study found that long-term aspirin use is associated with a lower risk of cancer overall, especially gastrointestinal tumors, and a 2020 study found that aspirin may reduce tumor growth and reduce the recurrence of CRC.
In the past, the United States Preventive Services Task Force recommended that most adults age 50 to 59 take a daily low-dose aspirin to prevent colorectal cancer. But the organization later retracted that recommendation, due in part to concerns that aspirin might increase the risk of gastrointestinal bleeding and the need for more research.
This possible link between aspirin and bleeding was a limitation of Tran and Nguyen's study, the researchers said.
“(The study) did not systematically evaluate potential side effects associated with aspirin use that may preclude long-term use,” the researchers explained. In other words, there are no data on how many people who take aspirin regularly develop bleeding or other complications, Tang noted.
“These findings seem promising, but future studies are needed to validate the results,” she said.
Although the study results were encouraging, it is too early to tell whether patients should begin aspirin therapy to prevent colon cancer, Diaz said.
“Suppressing inflammatory substances in the colon may prove to be safe and effective in reducing the risk of colon cancer,” he said, but more research is needed.
“Patients should discuss the relative risks and benefits with their doctor, who knows them best,” Diaz added.
If you're already taking aspirin under a doctor's supervision, for example to prevent recurrence of cardiovascular disease, “it may also lower your risk of colon cancer,” says Tan. If you're not currently taking aspirin, she recommends talking to your doctor before taking aspirin or any other medication.
Whether or not 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 protein, getting quality sleep, exercising and avoiding tobacco and alcohol, she advised.
“This study provides further evidence that making healthy lifestyle choices is one of the best ways to reduce your risk of developing cancer, including colorectal cancer,” she said. “And it's important that everyone gets recommended screenings, including colonoscopies.”
