In a recent publication in the Journal of the American Medical Association Oncology, researchers conducted a study to evaluate if aspirin correlates with colorectal cancer (CRC) risk across a diverse set of lifestyle risk factors.

This prospective cohort study included 107,655 study participants: 63,957 women who participated in the Nurses’ Health Study between 1980 and 2018 and 43,698 men in the Health Professionals Follow-Up Study between 1986 and 2018. The data were examined between October 1, 2021, and May 22, 2023.

The primary outcomes and measures for the study were the multivariable-adjusted 10-year cumulative incidence of CRC, absolute risk reduction (ARR), and number required to treat associated with regular aspirin use by lifestyle score and the multivariable-adjusted hazard ratios for incident CRC across lifestyle scores.

The participants’ average (SD) baseline age was 49.4 (9.0) years. During 3,038,215 person-years of follow-up, 2,544 incident cases of CRC were documented. The results revealed that among participants who regularly used aspirin, the 10-year cumulative CRC incidence was 1.98% (95% CI, 1.44%-2.51%) compared with 2.95% (95% CI, 2.31%-3.58%) among those who did not use aspirin, corresponding to an ARR of 0.97%. Moreover, the ARR related to aspirin use was greatest among those with the unhealthiest lifestyle scores and progressively diminished with healthier lifestyle scores (P <.001 for additive interaction). The 10-year ARR for lifestyle scores 0 to 1 (unhealthiest) was 1.28%.

The authors wrote, “In contrast, the 10-year ARR for lifestyle scores 4 to 5 (healthiest) was 0.11%. The 10-year number needed to treat with aspirin was 78 for participants with lifestyle scores 0 to 1, 164 for score 2, 154 for score 3, and 909 for scores 4 to 5.”

Additionally, among the components of the healthy lifestyle score, BMI and smoking were recorded as the most significant variances in ARR correlated with aspirin use.

Based on their findings, the authors concluded that in this cohort study of 107,655 men and women receiving aspirin and followed up for more than 3 decades, the use of aspirin was correlated with a greater ARR in the risk of CRC among individuals with less healthy lifestyles (i.e., higher BMI, greater amount of smoking, higher alcohol intake, less physical activity, and poorer diet quality), and these findings imply that lifestyle risk factors may be beneficial in detecting individuals who may have a more favorable risk-benefit profile for cancer prevention with aspirin.

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