Association between waist circumference and risk of colorectal neoplasia in normal-weight adults

Background and Aim: Abdominal obesity, measured using waist circumference (WC), is associated with the colorectal neoplasia (CRN) risk. We examined whether WC is associated with the CRN risk even in normal-weight individuals. Methods: A cross-sectional study was performed on asymptomatic normal-weight (body mass index 18.5–23 kg/m²) individuals who underwent colonoscopy as health checkups. Results: Of 63 057 examinees, 30 498 were men (mean age, 41.1 years) and 32 559 were women (mean age, 41.7 years). The prevalence of overall CRN in WC quartiles 1, 2, 3, and 4 was 14.2%, 15.5%, 15.5%, and 18.7%, respectively, in men and 7.4%, 8.9%, 9.4%, and 11.5%, respectively, in women. The prevalence of advanced CRN (ACRN) in WC quartiles 1, 2, 3, and 4 was 1.5%, 1.3%, 1.6%, and 2.1%, respectively, in men and 1.0%, 1.3%, 1.2%, and 1.3%, respectively, in women. Among men, the overall CRN risk in quartile 4 (> 82 cm) was higher than that in quartiles 1, 2, and 3 (adjusted odds ratio, OR [95% confidence interval, CI], 1.22 [1.11–1.34], 1.12 [1.05–1.23], and 1.18 [1.07–1.29], respectively); the ACRN risk in quartile 4 was also higher than that in quartiles 1, 2, and 3 (adjusted OR [95% CI], 1.41 [1.09–1.81], 1.56 [1.19–2.03], and 1.50 [1.16–1.94], respectively). Among women, the overall CRN risk in quartile 4 (> 77 cm) was higher than that in quartiles 1 and 3; the ACRN risk was not different among all groups. Conclusions: Even with a normal weight, a large WC was associated with the CRN risk, especially with the ACRN risk in men.