The association between metabolic syndrome and colorectal neoplasm: systemic review and meta-analysis.

Background: There has been constant speculation about the association between metabolic syndrome (MetS) and colorectal neoplasia (CN); however, the published results are conflicting. The aims of this study are to conduct a systematic search, and assess the literature to determine the available evidence on the association between these two conditions.

Methods: Meta-analysis was conducted based on relevant studies identified through a systematic literature review from PubMed, OvidSP, and Cochrane database during January 1980 to July 2011. A combined analysis was performed, followed by a subgroup analyses stratified by the study design, type of colorectal lesions, and sex. Publication bias was assessed using the Begg and Egger tests and visual inspection of funnel plot.

Results: Eighteen studies were included in the final analysis. Overall, MetS was associated with 34% increase in the risk of CN [summary relative risk (RR), 1.34; 95% confidence interval (CI), 1.24-1.44]. The association between MetS and CN was found to be statistically significant in separate analysis for both case-control studies (summary RR, 1.58; 95% CI, 1.44-1.73) and cohort studies (summary RR, 1.21; 95% CI, 1.13-1.29). The association remained significant when analyses were restricted by type of colorectal lesions (colorectal cancer: RR, 1.30; 95% CI, 1.18-1.43; colorectal adenoma: RR, 1.37; 95% CI, 1.26-1.49). Further subgroup analysis by sex showed significant association between MetS and CN in both male and female population.

Conclusions: Our meta-analysis showed significant association between presence of MetS and CN. These results may help in identifying high-risk individuals at early stage, who might benefit from targeted colorectal cancer screening intervention.