In a study reported in JAMA Oncology, Sikavi et al found that regular aspirin use was associated with a reduced risk of colorectal cancer overall and among individuals with less healthy vs more healthy lifestyles.
Study Details
The prospective cohort study focused on data from 107,655 participants from the Nurses’ Health Study (63,957 women) and the Health Professionals Follow-Up Study (43,698 men). For each participant, a healthy lifestyle score was calculated based on body mass index, alcohol intake, physical activity, diet, and smoking; scores ranged from 0 to 5 (higher score = healthier lifestyle). Regular aspirin use was defined as taking at least two standard tablets (325 mg) per week.
Key Findings
The mean baseline age of the 107,655 participants was 49.4 years (standard deviation = 9.0). During 3,038,215 person-years of follow-up, 2,544 incident cases of colorectal cancer were identified. The 10-year cumulative colorectal cancer incidence was 1.98% (95% confidence interval [CI] = 1.44%–2.51%) among subjects with regular aspirin use vs 2.95% (95% CI = 2.31%–3.58%) among those without regular aspirin use, corresponding to an absolute risk reduction of 0.97% among those with regular aspirin use.
The absolute risk reduction associated with regular aspirin use was highest among participants with the unhealthiest lifestyle scores and progressively decreased with healthier lifestyle scores (P < .001 for additive interaction). For example, the 10-year absolute risk reduction was 1.28% for lifestyle scores 0 to 1 (unhealthiest) and 0.11% for scores 4 to 5 (healthiest).
The 10-year number needed to treat with regular aspirin use to prevent 1 case of colorectal cancer was 78 for participants with lifestyle scores 0 to 1, 164 for those with a score of 2, 154 for those with a score of 3, and 909 for those with a score of 4 to 5.
On multivariate analysis, the greatest differences in absolute risk reduction associated with regular aspirin use were observed for body mass index of > 25.0 kg/m2 (1.19%), moderate/heavy smoking (1.20%), and moderate/heavy alcohol use (1.08%).
The investigators concluded: “In this cohort study, aspirin use was associated with a greater absolute reduction in risk of colorectal cancer among individuals with less healthy lifestyles. The findings of the study suggest that lifestyle risk factors may be useful to identify individuals who may have a more favorable risk-benefit profile for cancer prevention with aspirin.”
Andrew T. Chan, MD, MPH, and Long H. Nguyen, MD, MS, of the Clinical and Translational Epidemiology Unit, Massachusetts General Hospital and Harvard Medical School, are the corresponding authors of the JAMA Oncology article.
Disclosure: The study was supported by grants from the National Institutes of Health and others. For full disclosures of the study authors, visit jamanetwork.com.
