Aspirin may lower colorectal cancer risk for people with unhealthy lifestyles

Regular aspirin use may help lower the risk of colorectal cancer in people with greater lifestyle-related risk factors, according to a study led by researchers at Mass General Brigham. Published in JAMA Oncology, the study suggests a more nuanced approach to preventive aspirin use.

"We sought to identify individuals who are more likely to benefit from aspirin to facilitate more personalized prevention strategies," said co-senior author Andrew Chan, MD, MPH, Director of Epidemiology for the Mass General Cancer Center and gastroenterology Director of the Center for Young Adult Colorectal Cancer at Massachusetts General Hospital (MGH). Colorectal cancer is the second-leading cause of cancer death in the United States, according to the National Cancer Institute.

Previously, the U.S. Preventive Services Task Force recommended daily low-dose aspirin to prevent cardiovascular events and colorectal cancer in adults ages 50 to 59, the highest risk age group for colorectal cancer. However, in 2016, they withdrew the recommendation due to concerns about aspirin increasing the risk of gastrointestinal bleeding.

Researchers analyzed health data from 107,655 participants in the Nurses' Health Study and Health Professionals follow-up study. They compared colorectal cancer rates in those who took aspirin regularly with those who did not. Regular aspirin use was defined as either two or more standard dose (325 mg) tablets per week or daily low-dose (81 mg) aspirin.

Participants were followed starting from an average age of 49.4 years. Those who took aspirin regularly had a 10-year cumulative colorectal cancer incidence of 1.98 percent, compared to 2.95 percent among those who did not take aspirin.

The benefit of aspirin was largest among those with the unhealthiest lifestyles. Those with the lowest healthy lifestyle scores had a 3.4 percent chance of getting colorectal cancer if they did not take regular aspirin and a 2.12 percent chance if they did. In contrast, those with the highest healthy lifestyle scores had colorectal cancer rates of 1.5 percent in the regular aspirin group and 1.6 percent in the non-aspirin group. This indicates that in the least healthy group, treating 78 patients with aspirin would prevent one case of colorectal cancer over 10 years, while it would take treating 909 patients to prevent one case in the healthiest group. Lifestyle scores were based on body mass index, frequency of cigarette and alcohol use, physical activity, and adherence to a high-quality diet.

One outcome of the study is that "healthcare providers might more strongly consider recommending aspirin to patients who have less healthy lifestyles," said co-senior author Long H. Nguyen, MD, MS, a physician investigator in the Clinical and Translational Epidemiology Unit and Division of Gastroenterology at MGH and a Chen Institute Department of Medicine Transformative Scholar at MGH.

While the study included those who took regular standard-dose (325 mg) aspirin two times a week, Sikavi noted that based on prior studies, the best evidence supports daily low-dose (81 mg) aspirin for prevention.

Previous studies suggest that aspirin can reduce the production of pro-inflammatory proteins, known as prostaglandins, that can promote cancer development. Aspirin may also block signaling pathways that cause cells to grow out of control, influence the immune response against cancer cells, and block the development of blood vessels that supply nutrients to cancer cells. "Aspirin likely prevents colorectal cancer through multiple mechanisms," Chan said.

The study did not assess potential side effects of daily aspirin use, such as bleeding. Additionally, while the study controlled for a wide range of colorectal cancer risk factors, because it was observational, there may have been additional factors that influenced the findings.

Original source: https://www.news-medical.net/news/20240801/Aspirin-may-lower-colorectal-cancer-risk-for-people-with-unhealthy-lifestyles.aspx