Colorectal cancer ranks as the third most common cancer worldwide, with alarming statistics revealing that over 1.9 million people were newly diagnosed with the disease in 2020 alone.
Traditionally known to affect adults over the age of 50, recent trends indicate a disturbing rise in cases among younger populations, including children, teens, and young adults. This shift has prompted a closer examination of the factors contributing to the development of colorectal cancer, leading to new insights and prevention strategies.
The Role of Lifestyle Choices in Colorectal Cancer Risk
Previous studies have long established a connection between certain lifestyle choices and an increased risk of colorectal cancer. Factors such as smoking, excessive alcohol consumption, lack of physical activity, and unhealthy eating habits have all been linked to a higher likelihood of developing the disease. These risk factors are particularly concerning as they are modifiable, meaning individuals have the potential to lower their risk by making healthier choices.
Aspirin as a Potential Preventive Measure
In an effort to explore additional preventive measures, researchers from Massachusetts General Hospital and Harvard Medical School conducted a study to investigate the potential role of aspirin in reducing colorectal cancer risk.
The study, recently published in the journal JAMA Oncology, involved nearly 108,000 adults with an average age of 49. The participants were evaluated for five key lifestyle factors associated with colorectal cancer: body mass index (BMI), smoking, alcohol intake, physical activity, and diet. Each participant was then given a healthy lifestyle score ranging from zero to five.
In addition to lifestyle factors, the study also recorded the participants’ regular aspirin use, defined as taking two or more standard-sized tablets per week. Aspirin has been studied extensively for its potential to lower the risk of colorectal cancer, with past research suggesting a correlation between aspirin use and a reduction in the overall risk of recurrence and mortality associated with the disease.
Andrew T. Chan, MD, MPH, a professor of medicine at Harvard Medical School, chief of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital, director of epidemiology at the MGH Cancer Center, and co-corresponding author of this study, told Medical News Today, “Our group has contributed to the now-convincing body of literature that aspirin is effective in reducing the risk of colorectal cancer because there remains a critical unmet need for low cost, effective options for cancer prevention beyond screening, which is resource intensive and underutilized.”
“We are now focused on identifying who is most likely to benefit from regular aspirin use recognizing that aspirin also comes with side effects, such as gastrointestinal bleeding,” he said.
Significant Findings: Aspirin’s Impact on High-Risk Individuals
The participants in the study were followed for an extended period of 30 years, allowing researchers to observe the long-terms effects of aspirin use on colorectal cancer risk.
At the conclusion of the study, the data revealed a significant difference in the 10-year cumulative incidence of colorectal cancer between those who regularly took aspirin and those who did not. Specifically, the incidence was 1.98% among aspirin users compared to 2.95% among non-users.
When researchers analyzed the data further, they discovered that the greatest reduction in colorectal cancer risk occurred in participants with the unhealthiest lifestyle scores. These individuals, who were already at a higher risk due to factors such as high BMI and smoking, experienced the most substantial benefit from regular aspirin use.
“We observed that participants in our study with the least healthy lifestyle, as assessed by higher body mass index, more smoking, greater alcohol use, less physical activity, and poorer diet quality, had the greatest absolute benefit from aspirin use,” noted Long H. Nguyen, MD, MS, a physician investigator and core faculty at the Clinical and Translational Epidemiology Unit, assistant professor of medicine and gastroenterology at the Massachusetts General Hospital and Harvard Medical School, and co-corresponding author of this study explained to MNT.
“These participants had multiple risk factors that increased their overall risk of developing colorectal cancer, and our results show that aspirin can proportionally lower this comparably elevated risk. In contrast, those with a healthier lifestyle had a lower baseline risk of colorectal cancer, and therefore, their benefit from aspirin was still evident, but less pronounced. This fits with our pre-study hypothesis.”
Understanding Aspirin’s Mechanisms in Cancer Prevention
The study’s findings contribute to the growing understanding of how aspirin may help prevent colorectal cancer. According to Dr. Chan, aspirin likely works through multiple mechanisms.
“One major pathway is the reduction in inflammation, including the production of specific proinflammatory proteins known as prostaglandins that can promote the development of cancer,” he explained.
“Aspirin also appears to block signaling pathways within cells that cause them to grow and spread. Finally, aspirin may additionally influence the immune response against cancer cells and block the development of blood vessels that supply nutrients to growing cancer cells,” Dr. Chan adds.
Given the complexity of these mechanisms, Dr. Chan emphasized the importance of targeted research to identify which individuals are most likely to benefit from aspirin use.
“Given the current emphasis on targeted therapies and precision cancer prevention, more studies like this one are needed to move beyond one-size-fits-all universal strategies that do not adequately account for other personal risk factors,” Dr. Chan continued.
“We plan additional studies to further refine our understanding of the specific patient subgroups most likely to benefit from aspirin prevention and also large-scale international studies to identify additional lifestyle and pharmacologic strategies for cancer prevention,” Dr. Nguyen added.
The Need for Caution: Potential Side Effects of Aspirin
While the study’s findings are promising, experts caution that aspirin use is not without risks. Anton J. Bilchik, MD, a surgical oncologist and director of the Gastrointestinal and Hepatobiliary Program at Providence Saint John’s Cancer Institute, highlighted the potential side effects of aspirin, particularly gastrointestinal bleeding.
“There’s been a lot of discussion about the preventative role of aspirin in colorectal cancer, since it’s well known that aspirin has been shown to reduce the incidence of colorectal cancer,” Dr. Bilchik continued.
“But at the same time, there has also been concern about the potential side effects of aspirin in particular gastritis and bleeding from the stomach. So trying to better understand which patients to treat with aspirin and which patients not to treat is very important information.”
“There are lifestyle modification factors that are likely to be even more relevant and more important than aspirin, such as weight reduction, exercise, prevention of smoking, as well as dietary modifications – eating healthy, reducing the intake of processed food – so many other factors to take into account,” Dr. Bilchik adds.
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