Lifestyle factors impact aspirin’s effect on colorectal cancer prevention
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Key takeaways:
- Regular aspirin use reduced risk for colorectal cancer in a large prospective cohort study.
- Individuals with high BMI, as well as those considered moderate or heavy smokers, derived the most benefit.
Individuals with unhealthy lifestyles may derive the most benefit from aspirin for colorectal cancer prevention, according to results of a prospective cohort study.
Regular aspirin use conferred a reduction in 10-year cumulative colorectal incidence in the entire cohort; however, individuals with a high BMI, those classified as moderate or heavy smokers, and those who reported moderate or heavy alcohol consumption had the most significant risk reductions.
“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,” researcher Daniel R. Sikavi, MD, fellow at Massachusetts General Hospital, told Healio.
Background and methodology
Previous research showed aspirin can lower risk for colorectal cancer by as much as 30%, according to study background.
In 2016, the U.S. Preventive Services Task Force published a recommendation statement indicating that aspirin is a viable approach for colorectal cancer prevention. However, the task force revised this recommendation in 2022 due to concerns about whether the benefits outweighed potential risks, including bleeding.
More research is needed to determine who would derive the most benefit from aspirin, researchers wrote.
Sikavi and colleagues evaluated whether the impact of aspirin use on colorectal cancer risk varied based on lifestyle factors.
They analyzed data from 107,655 people (mean age, 49.4 years) — 63,957 women who participated in the Nurses’ Health Study and 43,698 men who participated in the Health Professionals Follow-up Study.
Investigators defined regular aspirin use as at least two standard 325-mg tablets weekly.
Results and next steps
After more than 3.03 million person-years of follow-up, researchers documented 2,544 colorectal cancer cases.
Regular aspirin users had a lower 10-year cumulative incidence of colorectal cancer (1.98%; 95% CI, 1.44-2.51) than nonregular users (2.95%; 95% CI, 2.31-3.58).
Researchers analyzed incidence based on study participants’ healthy lifestyle scores. The 5-point scale — with higher values representing healthier lifestyles — accounted for diet, BMI, physical activity, smoking and alcohol consumption.
Individuals with lower lifestyle scores (0 or 1) had a higher 10-year absolute risk reduction than those with lifestyle scores of 4 or 5 (1.28% vs. 0.11%).
those who have less than 30 minutes of physical activity per day (0.91%; P < .001 for all).
Multivariable analysis showed greater 10-year absolute risk reductions among those with BMI higher than 25 mm/kg2 vs. BMI 18.5 to 25 mm/kg2 (1.19% vs. 0.56%), moderate/heavy smokers vs. never/minimal smokers (1.2% vs. 0.75%), those with moderate/heavy alcohol consumption vs. no/minimal consumption (1.08% vs. 0.87%), and those with less than 30 minutes of daily physical activity vs. 30 minutes or more (1.88% vs. 1.37%; P < .001 for all comparisons).
“These individuals had multiple risk factors that increased their overall risk for developing colorectal cancer,” Sikavi said. “Our results show that aspirin can proportionally lower this comparatively elevated risk. In contrast, those with a healthier lifestyle might have a lower baseline risk and, therefore, their benefit was still evident but less pronounced.”
Sikavi and colleagues acknowledged several limitations to their study. including the lack of racial and ethnic diversity in the cohort; the fact the cohort consisted of health care professionals, who tend to have healthier lifestyles; and reliance on self-reported use of aspirin.
“We intend to further refine our understanding of the specific patient subgroups most likely to benefit from aspirin for colorectal cancer prevention and also plan large-scale international studies on how best to intervene with other lifestyle or pharmacologic adjuncts to lower their risk even further,” Sikavi said. “This work is an example of how we can move beyond one-size-fits-all strategies for cancer prevention by targeting effective preventive agents such as aspirin to the populations that are the most likely to benefit.”
For more information:
Daniel R. Sikavi, MD, can be reached at dsikavi@mgh.harvard.edu.
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