Comparison of associations of body mass index, abdominal adiposity, and risk of colorectal cancer in a large prospective cohort study
Menée en Allemagne auprès de 203 177 participants suivis pendant 10 ans, cette étude de cohorte prospective évalue et compare l'association entre l'indice de masse corporelle, l'adiposité abdominale (mesurée par le tour de taille et le ratio taille-hanche), et le risque de cancer colorectal
Background: Increased body-mass-index (BMI) is an established colorectal cancer (CRC) risk factor. High waist circumference (WC) or waist-hip-ratio (WHR) may better reflect an abnormal metabolic state and be more predictive of CRC risk than BMI. Methods: We examined BMI, WC, WHR, and hip circumference (HC) in relation to CRC risk among 203,177 participants followed for ten years. We derived standardized CRC risk estimates for each anthropometric parameter and compared predictive characteristics (Harrell's C-index). In women, we examined whether hormone replacement therapy (HRT) use modified the associations between anthropometric measures and CRC. Results: We ascertained 2,869 CRCs. In men, increased colon cancer risks were associated with BMI (HR per standard deviation (SD)=1.14, 95%CI=1.08-1.20), WC (HR per SD=1.17, 95%CI=1.08-1.27), and WHR (HR per SD=1.09, 95%CI=1.04-1.14). In women, anthropometric variables were unrelated to colon cancer. For men and women, anthropometric variables were unrelated to rectal cancer. Compared with BMI, WC and WHR did not materially influence colon cancer prediction models (C-index-changes: -0.0041 and 0.0046 (men); 0.0004 and 0.0005 (women)). In current HRT users, colon cancer was inversely or suggestively inversely associated with WC (HR per SD=0.78, 95%CI=0.63-0.97) and WHR (HR per SD=0.88, 95%CI=0.76-1.01), but positively related to HC (HR per SD=1.39, 95%CI=1.13-1.71). Conclusion: BMI, WC, and WHR show comparable positive associations with colon cancer in men. Associations between anthropometric measures and colon cancer are weak or null in women, but there is some evidence for effect modification by HRT. Impact: These findings may improve our understanding of the relation of adiposity to CRC.