title: Comparison of associations of body mass index, abdominal adiposity, and risk of colorectal cancer in a large prospective cohort study.
abstract: BACKGROUND
  Increased body mass index (BMI) is an established colorectal cancer risk factor. High waist circumference or waist-hip-ratio (WHR) may better reflect an abnormal metabolic state and be more predictive of colorectal cancer risk than BMI.
  
  
  METHODS
  We examined BMI, waist circumference, WHR, and hip circumference in relation to colorectal cancer risk among 203,177 participants followed for 10 years. We derived standardized colorectal cancer 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 colorectal cancer.
  
  
  RESULTS
  We ascertained 2,869 colorectal cancers. In men, increased colon cancer risks were associated with BMI [HR per SD, 1.14; 95% confidence interval (CI), 1.08-1.20], waist circumference (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, waist circumference 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 waist circumference (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 hip circumference (HR per SD, 1.39; 95% CI, 1.13-1.71).
  
  
  CONCLUSIONS
  BMI, waist circumference, 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.
  
  
  CONCLUSIONS
  These findings may improve our understanding of the relation of adiposity to colorectal cancer.
authors.affiliation: Department of Epidemiology and Preventive Medicine, Regensburg University Medical Center, Regensburg, Germany. Marlen.Keimling@ukr.de
authors.forename: Marlen
authors.initials: M
authors.lastname: Keimling
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Renehan
authors.forename: Gundula
authors.initials: G
authors.lastname: Behrens
authors.forename: Beate
authors.initials: B
authors.lastname: Fischer
authors.forename: Albert R
authors.initials: AR
authors.lastname: Hollenbeck
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Cross
authors.forename: Michael F
authors.initials: MF
authors.lastname: Leitzmann
mesh_terms: D050154:Adiposity; D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D011446:Prospective Studies; D014481:United States / Q000453:epidemiology; D055105:Waist Circumference