Metabolic syndrome and risk of colorectal adenoma and colorectal cancer: A meta-analysis

Background: Growing evidence suggests that metabolic syndrome (MetS) could be linked with the incidence of colorectal adenoma and cancer (CRA and CRC). Aim:  Conducting a meta-analysis to assess the association of MetS with both CRA and CRC. Methods and Material:  Relevant studies were identified by systematically searching PubMed database for articles published in the last ten years. A random effect analysis model and Mantel-Haenszel statistical method were used to obtain pooled risk ratios (RRs) and their 95% confidence intervals (CIs) for dichotomous data. The analyses were assessed for heterogeneity and publication bias. Results:  35 studies were included in the meta-analysis involving approximately 1300000 participants. A significant high risk for CRA was observed among patients with MetS compared to those without (RR = 1.43; 95% CI = 1.31, 1.57). The pooled RRs of CRC were 1.46 (95% CI = 1.36, 1.56). The risk estimates varied according to the type of the study (cohorts and non-cohorts), gender (men and women), MetS definition (NCEP-ATPIII, IDF, harmonized and others), populations (Asia, Europe, and the USA), and cancer location (colon and rectum). Conclusions: MetS is associated with an increased risk of CRA and CRC. The risk was higher for advanced adenomas. Taking into consideration MetS patients in the secondary prevention programs and the management of this condition in the aim of the primary prevention is highly recommended.