Aspirin, long recognized for its benefits in heart health, may also serve as a potential preventive measure against colorectal cancer, particularly in people with certain lifestyle risk factors.
A recent study highlights aspirin’s potential to reduce the risk of colorectal cancer in individuals who engage in behaviors such as smoking, excessive alcohol consumption, and physical inactivity.
While not definitive, this research sheds light on how aspirin may work to protect against cancerous growths in the colon, especially for those at higher risk due to lifestyle factors.
A Three-Decade Study on Aspirin Use and Cancer Prevention
Researchers tracked over 100,000 men and women over a period of thirty years, starting when participants were, on average, 49 years old. Throughout the study, scientists compared colorectal cancer rates between regular aspirin users and those who did not routinely use aspirin. Regular users were defined as individuals taking at least two standard 325-milligram doses per week or one low-dose 81-milligram pill daily.
The results of the study, published in JAMA Oncology, revealed a significant difference in cancer incidence between these two groups.
The 10-year colorectal cancer rate was 1.98% among regular aspirin users compared to 2.95% among non-users. Although this suggests a potential benefit of aspirin use, the effect was not uniform across all participants.
Those with unhealthy lifestyle factors—such as smoking, poor diet, inactivity, and obesity—saw the most significant reduction in cancer risk. For this group, the 10-year incidence was 2.12% with regular aspirin use compared to 3.4% without it.
In contrast, the benefit for individuals with healthier lifestyles was smaller. Among these lower-risk participants, the 10-year cancer incidence was 1.5% with aspirin use and 1.6% without it.
According to senior study author Andrew Chan, MD, MPH, a gastroenterologist at Massachusetts General Hospital Cancer Center, “Aspirin still reduces the risk of colorectal cancer in those with the healthiest lifestyle. However, the absolute total benefit is not as strong because they were at low risk to begin with.”
For those at a lower baseline risk, the marginal decrease may not provide enough reason to incorporate aspirin solely for cancer prevention.
How Aspirin Could Help Prevent Colorectal Cancer
While the study was not designed to determine exactly how aspirin might prevent colorectal cancer, researchers have several theories. Dr. Chan explains that aspirin’s primary impact on cancer prevention may lie in its ability to reduce inflammation, a factor known to contribute to tumor growth.
Additionally, aspirin can inhibit signaling pathways that allow cancer cells to grow and spread. This interference may prevent the formation of new blood vessels that tumors rely on for nourishment, effectively starving the cancer cells. Aspirin may also enhance the immune system’s response to abnormal cells, providing further protection against the spread of cancerous cells.
Dr. Chan noted that aspirin’s benefits could be particularly pronounced for people with unhealthy lifestyles since these individuals are likely to have elevated levels of inflammation, which could encourage cancer growth. By reducing inflammation in these high-risk individuals, aspirin may offer a buffer against colorectal cancer in addition to addressing heart health risks.
Potential Risks of Regular Aspirin Use
Despite its benefits, regular aspirin use comes with significant risks. Michael Hall, MD, chairman of the clinical genetics department at Fox Chase Cancer Center, points out that aspirin use can lead to side effects ranging from minor to severe.
Common side effects include easy bruising, prolonged bleeding times for minor cuts, more intense menstrual cycles, and stomach discomfort. More serious complications can include gastrointestinal bleeding, severe gastritis, and even kidney issues.
Because of these risks, in 2022, the U.S. Preventive Services Task Force revised its guidelines, removing the recommendation for daily aspirin use in colorectal cancer prevention for individuals without specific health conditions. While aspirin still offers cardiovascular benefits, especially for those with a history of heart disease, its potential to cause bleeding makes daily use questionable, particularly for cancer prevention alone.
Balancing Aspirin’s Benefits and Risks by Age
The findings suggest that age plays a significant role in balancing aspirin’s benefits and risks.
According to Lenard Lichtenberger, PhD, professor emeritus at the University of Texas Health Science Center, younger adults under 60 may be better candidates for preventive aspirin use.
“People under 60 years old are most likely to benefit, while older individuals are at higher risk for bleeding with regular aspirin use,” Dr. Lichtenberger explains.
For older adults, daily aspirin may still be beneficial for cardiovascular disease prevention, but the anti-cancer benefits must be weighed against the increased risk of gastrointestinal ulceration and bleeding. Dr. Hall agrees, suggesting that individuals with high-risk lifestyle factors—such as smoking, obesity, and inactivity—could consider starting aspirin earlier in life.
“A 30-year-old with multiple unhealthy lifestyle factors could consider taking preventive aspirin to mitigate future cancer risk while they are at a time in their life when the risk of using aspirin is low and when they can safely accrue future protective benefits as they move into their forties and fifties,” Dr. Hall suggests.
Understanding Who May Benefit Most
A key limitation of this study, as Dr. Hall points out, is that it does not conclusively identify who would benefit most from aspirin for cancer prevention. As the risk of bleeding increases with age, understanding the ideal candidates for aspirin use remains a challenge.
Further research is needed to determine whether there is a specific risk threshold for colorectal cancer that would make daily aspirin a more favorable option. Until that data is available, aspirin’s role in cancer prevention remains somewhat individualized, with benefits hinging on personal health histories and lifestyle risks.
Considerations for Aspirin Use in Cancer Prevention
Aspirin’s potential for cancer prevention should be considered alongside each person’s lifestyle, risk factors, and age. Those at higher risk due to lifestyle factors may find value in daily aspirin use for its anti-inflammatory properties, while those with lower risk may benefit less. With the significant risks of regular aspirin use—especially for gastrointestinal health—it is important to consult a healthcare provider to weigh the advantages and disadvantages carefully.
This study underscores the importance of lifestyle choices in cancer prevention. For people at high risk, a combination of lifestyle adjustments alongside preventive measures like aspirin may offer the best outcomes. As more data emerge on aspirin’s effects on colorectal cancer, individuals can make better-informed decisions on incorporating it into their preventive health strategies.
While aspirin holds promise as a cancer-prevention tool, it is not without risks, and it may not be suitable for everyone. Balancing lifestyle choices and consulting medical professionals can help individuals determine the most appropriate approach to their cancer prevention strategies.
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