Association of visceral fat accumulation and plasma adiponectin with colorectal adenoma: evidence for participation of insulin resistance.

PURPOSE Colorectal carcinogenesis is thought to be related to abdominal obesity and insulin resistance. To investigate whether visceral fat accumulation contributes to colorectal carcinogenesis, we examined its accumulation and the levels of the adipose tissue-derived hormone adiponectin in Japanese patients with colorectal adenoma. EXPERIMENTAL DESIGN Fifty-one consecutive Japanese patients ages >/=40 years and with colorectal adenoma were subjected to measurement of visceral fat area by computed tomography scanning and plasma adiponectin concentration. The patients also underwent the 75-g oral glucose tolerance test. Insulin resistance was calculated by the homeostasis metabolic assessment (HOMA-IR) method. The controls were 52 Japanese subjects ages >/=40 years and without colorectal polyp. Cigarette smokers and subjects who consumed alcohol (>/=30 g ethanol/d) were excluded. RESULTS The patients with colorectal adenoma showed significantly more visceral fat area and significantly less plasma adiponectin concentration in comparison with the controls [odds ratio (OR), 2.19; 95% confidence interval (95% CI), 1.47-3.28; P < 0.001 and OR, 0.24; 95% CI, 0.14-0.41; P < 0.001, respectively] by logistic regression analysis. HOMA-IR index was also associated with colorectal adenoma (OR 2.60; 95% CI, 1.20-5.64; P = 0.040). Visceral fat area and adiponectin were associated with adenoma number (1, 2, >/= 3), the size of the largest adenoma (<10 and >/=10 mm), and adenoma histology (tubular and tubulovillous/villous). CONCLUSIONS These results suggest an association of visceral fat accumulation and decreased plasma adiponectin concentration with colorectal adenoma in Japanese patients. This study may offer a new insight to understanding the relationship of colorectal carcinogenesis with abdominal obesity and insulin resistance.