Aspirin for CRC prevention works better in presence of less healthy lifestyles

People with less healthy lifestyles appear to obtain greater protection against colorectal cancer (CRC) with aspirin use, according to a study.

Researchers used data from the Nurses’ Health Study (1980-2018) and the Health Professionals Follow-Up Study (1986-2018). A composite healthy lifestyle score was constructed using data on BMI, alcohol consumption, physical activity levels, dietary patterns, and smoking status. Scores ranged from 0 to 5, with higher scores indicating a healthier lifestyle. Regular aspirin use was defined as intake of two or more standard tablets (325 mg) per week.

A total of 107,655 adults (mean age at baseline 49.4 years) participated in the study, including 63,957 women from the Nurses’ Health Study and 43,698 men from the Health Professionals Follow-Up Study. There were 2,544 incident cases of CRC documented over 3,038,215 person-years of follow-up.

The 10-year cumulative CRC incidence was lower among participants who regularly used aspirin at 1.98 percent (95 percent confidence interval [CI], 1.44–2.51) than among those who did not use aspirin at 2.95 percent (95 percent CI, 2.31–3.58), yielding an absolute risk reduction (ARR) of 0.97 percent.

Notably, participants with the lowest lifestyle scores had the greatest ARR with aspirin use, and the ARRs progressively decreased as lifestyle scores increased (p<0.001 for interaction). Specifically, the 10-year ARR was 1.28 percent for lifestyle scores 0–1 as opposed to 0.11 percent for lifestyle scores 4–5.

The 10-year number needed to treat with aspirin was 78 for participants with lifestyle scores 0–1, 164 for those with lifestyle score 2, 154 for those with lifestyle score 3, and 909 for those with lifestyle scores 4–5.

Among the components of the healthy lifestyle score, BMI and smoking were the primary lifestyle factors influencing aspirin's risk reduction.

The greatest disparities in aspirin-associated ARR were observed for BMI and smoking status among the various components of the healthy lifestyle score.