Visceral adipose tissue and the risk of colorectal adenomas: a meta-analysis of observational studies

Visceral adipose tissue (VAT)-related metabolic syndromes are hypothesized to promote colorectal neoplasia; however, the results from studies investigating whether VAT directly measured by computed tomography is a risk factor for colorectal adenomas (CRA) have been inconsistent. We carried out a meta-analysis of epidemiological studies to quantitatively assess this association and dose-response relationship between VAT and the risk of CRA. We searched PubMed for relevant studies that were published in any language, from January, 1950 to June, 2010. Three case-control studies and eight cross-sectional studies involving 11111 participants contributed toward this meta-analysis. We pooled the odds ratio (OR) from individual studies and carried out dose-response, heterogeneity, and publication bias analyses. In a pooled analysis of all studies, the amount of VAT (in a comparison of the highest and lowest categories) was associated with an increased risk of CRA (OR=1.67, 95% confidence interval: 1.29-2.16). Subgroup meta-analyses by both sexes, VAT measurements, study designs, and Asian ethnicity yielded similar results. An increase of 500cm(3) of VAT volume was related to an increased risk of CRA from the dose-response meta-analysis (OR=1.06; 95% confidence interval: 1.03-1.11). These results suggest that a large amount of VAT measured by computed tomography significantly increases the risk of CRA both in men and in women.