Association of visceral adiposity and insulin resistance with colorectal adenoma and colorectal cancer

BACKGROUND/AIMS: To examine whether visceral adiposity serves as a risk factor for colorectal cancer (CRC) and colorectal adenomas. METHODS: Two hundred healthy subjects, 200 patients with colorectal adenoma, and 151 patients with CRC (46 with early-stage and 105 with advanced-stage cancers) were enrolled at a tertiary referral hospital. All subjects underwent colonoscopy, and had laboratory data, and computed tomography (CT) scan available for abdominal fat measurement. An abdominal CT scan taken 1 to 4 years (mean interval, 20.6 months) before the diagnosis of CRC was also available in the 42 CRC patients. RESULTS: The mean areas of visceral adipose tissue (VAT) areas in the control, adenoma, early- and advanced-stage CRC groups were 94.6, 116.8, 110.4, and 99.7 cm(2), respectively (P<0.001). The risk of adenoma positively correlated with VAT area and the visceral-to-total fat ratio (P for trend <0.01), but the risk of CRC did not (P>0.05). The risk of both adenoma and CRC positively correlated with fasting plasma glucose levels (P for trend <0.05). In patients with early-stage cancer (n=17), VAT area decreased when the CT scan at diagnosis was compared with that taken before the diagnosis of CRC, but superficial adipose tissue area did not, so visceral-to-total fat ratio significantly decreased (46.6% vs. 50.7%, respectively, P=0.018) CONCLUSIONS: VAT area is related to the risk of colorectal adenoma. However, VAT decreases from the early stages of CRC. Impaired fasting glucose has a role in colorectal carcinogenesis.