Self-reported and measured anthropometric data and risk of colorectal cancer in the EPIC-Norfolk study.

BACKGROUND: Epidemiological studies have shown inconsistent results for the association between body size and colorectal cancer (CRC) risk. Inconsistencies may be because of the reliance on self-reported measures of body size. OBJECTIVE: We examined the association of self-reported and directly assessed anthropometric data (body height, weight, body mass index (BMI), waist, hip, waist-to-hip ratio (WHR) and chest circumference) with CRC risk in the EPIC-Norfolk study. DESIGN: A total of 20,608 participants with complete self-reported and measured height and weight and without any history of cancer were followed up an average of 11 years, during which 357 incident CRC cases were recorded. Hazard Ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. RESULTS: After adjustment for confounders, HRs among women in the highest quintile of the body size measure relative to the lowest quintile showed that measured height (HR=1.98, 95% CI=1.19-3.28, P (trend)=0.009), measured waist circumference (HR=1.65, 95% CI=0.97-2.86, P (trend)=0.009) and measured WHR (HR=2.07, 95% CI=1.17-3.67, P (trend)=0.001) were associated with increased CRC risk. Associations using corresponding self-reported measures were attenuated and not statistically significant. Conversely, the association of BMI with CRC risk in women was weaker using measured BMI (HR=1.57, 95% CI=0.91-2.73, P (trend)=0.05) compared with self-reported BMI (HR=1.97, 95% CI=1.18-3.30, P (trend)=0.02). In men no significantly increased CRC risk was observed with any of the anthropometric measures. CONCLUSIONS: Measured height, waist circumference and WHR were associated with CRC risk in women, whereas any significant associations with those measures were attenuated when self-reported data were used