Aspirin for CRC Prevention Best in Unhealthy Lifestyles

TOPLINE:
Aspirin provides greater protection against colorectal cancer (CRC) in people with unhealthy lifestyles, particularly smokers with higher body weight, new data suggest. 
METHODOLOGY:
Aspirin is an established agent for CRC prevention. Whether individuals with more lifestyle risk factors might derive greater benefit from aspirin remains unclear.
Researchers analyzed regular aspirin use (defined as taking two or more standard 325-mg tablets per week) using long-term follow-up data from 63,957 women in the Nurses’ Health Study and 43,698 men in the Health Professionals Follow-Up Study.
They calculated a healthy lifestyle score for each participant based on body mass index (BMI), alcohol intake, physical activity, diet, and smoking, with higher scores corresponding to healthier lifestyles.
Outcomes included multivariable-adjusted 10-year cumulative incidence of CRC, the absolute risk reduction (ARR) with aspirin use, and number needed to treat associated with regular aspirin use by lifestyle score.
TAKEAWAY:
During more than three million person-years of follow-up, 2544 new cases of CRC were documented.
The 10-year cumulative incidence of CRC was 1.98% among regular aspirin users compared with 2.95% among nonusers, corresponding to an ARR of 0.97%.
The ARR associated with aspirin use was greatest among individuals with the unhealthiest lifestyle scores and progressively decreased with healthier lifestyle scores (P <.001 for additive interaction).
Those with the unhealthiest lifestyle scores (0-1) had a 10-year ARR of 1.28% from aspirin use, whereas those with the healthiest lifestyle scores (4-5) had an ARR of 0.11%.
The number needed to treat with aspirin for 10 years to prevent one CRC case was 78 for those with the unhealthiest lifestyles, compared with 909 for those with the healthiest lifestyles.
Among the individual components of the healthy lifestyle score, higher BMI and smoking correlated with greater reductions in CRC risk from aspirin use.
IN PRACTICE:
“These results support the use of lifestyle risk factors to identify individuals who may have a more favorable risk-benefit profile for cancer prevention with aspirin,” the authors wrote. 
SOURCE:
The study, with first author Daniel R. Sikavi, MD, from Massachusetts General Hospital and Harvard Medical School in Boston, was published online in JAMA Oncology.
LIMITATIONS:
The study population consisted of health professionals who were predominantly White, which may limit generalizability of the findings. Lifestyle factors and aspirin use were self-reported, which may introduce measurement errors. The study did not systematically assess adverse outcomes potentially due to aspirin use or the presence of a known hereditary cancer syndrome. 
DISCLOSURES:
The study had no commercial funding. The authors had no relevant conflicts of interest.
 
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