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Aspirin Use for Colorectal Cancer Prevention: Association With Lifestyle Risk Factors
TAKE-HOME MESSAGE
- This prospective cohort study assessed the effect of aspirin use on the risk of colorectal cancer (CRC) across different lifestyle risk factors. Study participants (N = 107,655) were followed for more than 30 years. The 10-year absolute risk reduction of CRC associated with aspirin use was larger among participants with unhealthier lifestyles (higher BMI, heavy smokers) than among those with healthier lifestyles. However, the relative reduction in CRC incidence associated with aspirin use was comparable between the two groups.
- This study suggests that aspirin may be useful for CRC prevention in individuals with higher lifestyle risk factors for CRC.
abstract
This abstract is available on the publisher's site.
Access this abstract nowIMPORTANCE
Aspirin reduces the risk of colorectal cancer (CRC). Identifying individuals more likely to benefit from regular aspirin use for CRC prevention is a high priority.
OBJECTIVE
To assess whether aspirin use is associated with the risk of CRC across different lifestyle risk factors.
DESIGN, SETTING, AND PARTICIPANTS
A prospective cohort study among women in the Nurses' Health Study (1980-2018) and men in the Health Professionals Follow-Up Study (1986-2018) was conducted. Data analysis was performed from October 1, 2021, to May 22, 2023.
EXPOSURES
A healthy lifestyle score was calculated based on body mass index, alcohol intake, physical activity, diet, and smoking with scores ranging from 0 to 5 (higher values corresponding to a healthier lifestyle). Regular aspirin use was defined as 2 or more standard tablets (325 mg) per week.
MAIN OUTCOME AND MEASURES
Outcomes included multivariable-adjusted 10-year cumulative incidence of CRC, absolute risk reduction (ARR), and number needed to treat associated with regular aspirin use by lifestyle score and multivariable-adjusted hazard ratios for incident CRC across lifestyle scores.
RESULTS
The mean (SD) baseline age of the 107 655 study participants (63 957 women from the Nurses' Health Study and 43 698 men from the Health Professionals Follow-Up Study) was 49.4 (9.0) years. During 3 038 215 person-years of follow-up, 2544 incident cases of CRC were documented. The 10-year cumulative CRC incidence was 1.98% (95% CI, 1.44%-2.51%) among participants who regularly used aspirin compared with 2.95% (95% CI, 2.31%-3.58%) among those who did not use aspirin, corresponding to an ARR of 0.97%. The ARR associated with aspirin use was greatest among those with the unhealthiest lifestyle scores and progressively decreased with healthier lifestyle scores (P < .001 for additive interaction). The 10-year ARR for lifestyle scores 0 to 1 (unhealthiest) was 1.28%. 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. Among the components of the healthy lifestyle score, the greatest differences in ARR associated with aspirin use were observed for body mass index and smoking.
CONCLUSIONS AND RELEVANCE
In this cohort study, aspirin use was associated with a greater absolute reduction in risk of CRC 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.
Additional Info
Disclosure statements are available on the authors' profiles:
Aspirin Use and Incidence of Colorectal Cancer According to Lifestyle Risk
JAMA Oncol 2024 Aug 01;[EPub Ahead of Print], DR Sikavi, K Wang, W Ma, DA Drew, S Ogino, EL Giovannucci, Y Cao, M Song, LH Nguyen, AT ChanFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Aspirin use in the context of lifestyle for prevention of colorectal cancer
Aspirin (ASA) has been shown to reduce the risk of colorectal cancer (CRC) in the general population — and particularly in the setting of Lynch syndrome — however, the reported data in the general population have been inconsistent. It appears that ASA must be taken for an extended period (8 years or more) to achieve a preventive benefit, diminishing the value of short-term studies. Additionally, there have been concerns about the possible risks associated with regular ASA use, leading some to seek more precise guidelines for its use.
Sikavi et al have reported their results of a prospective study of ASA use and CRC incidence in two large cohorts studied since the 1980s — the Nurses’ Health Study involving 63,957 women and the Health Professionals Follow-up Study involving 43,698 men. Baseline age for inclusion in the study was 49.4 years. These cohorts have been well-documented and the source of valuable data in the past. In this analysis, Sikavi et al calculated the absolute risks of CRC among those taking two or more 325-mg doses of ASA per week, and examined the impact of five lifestyle factors on outcome, including BMI, ethanol intake, physical activity, diet, and smoking habits, yielding scores from 0 (worst scores) to 5 (best scores). The 10-year cumulative risks for CRC were 1.98% among ASA users and 2.95% among nonusers for an absolute risk reduction of 0.97% (about half). Risk reduction was greatest for those with unhealthy lifestyle scores, being 1.28% among those with scores of 0 to 1 versus 0.11% among those with scores of 4 to 5. The number needed to treat to prevent CRC was 78 in the low-score group versus 909 in the high-score group.
This is a key study to assist in the development of more precise approaches to the use of ASA in the context of CRC prevention in the general population. One must treat a fairly large number of healthy individuals to prevent CRC; however, this is a serious disease worth the efforts of prevention. One gets greater benefit by treating those with unhealthy lifestyles, and one could justify not using ASA in those with very high (healthy) lifestyle scores. These cohorts are all healthcare professionals and were predominantly White individuals, which may need to be considered when making generalized recommendations. However, these are well-documented cohorts that have been studied prospectively for 32 to 38 years, and the data should be taken very seriously. This study provides novel insights into how to use ASA as a cancer-preventive medication.