A prospective study of waist circumference and body mass index in relation to colorectal cancer incidence

Objectives To study the association between waist circumference and colorectal cancer, and whether it is independent of body mass index (BMI). Methods Between 1997 and 2005, 953 incident colorectal cancer cases (546 men and 407 women) were identified among 95,151 participants (44,068 men and 51,083 women) from the Cancer Prevention Study-II Nutrition Cohort. Results Waist circumference was associated with increased colorectal cancer incidence in both men (multivariable adjusted rate ratio (RR) 1.68, 95% confidence interval (CI) 1.12-2.53 for waist circumference >= 120 cm compared to < 95 cm, p trend = 0.006) and women (RR 1.75, 95% CI 1.20-2.54 for >= 110 compared to < 85 cm, p trend = 0.003). High levels of BMI were also associated with increased risk. After adjustment for BMI, waist circumference remained associated with a nonstatistically significant increase in colorectal cancer incidence in both men (RR 1.41, 95% CI 0.81-2.45 for >= 120 compared to < 95 cm, p trend = 0.10) and women (RR 1.48, 95% CI 0.89-2.48 for >= 110 compared to < 85 cm, p trend = 0.13). Conclusions Our results confirm that waist circumference is associated with increased colorectal cancer incidence, possibly partially independent of BMI.