LAUSR

OBJECTIVE Whether metabolic syndrome is a risk factor of colorectal adenoma has spurred debate. We systematically meta-analyzed all clinical studies associated with metabolic syndrome (MetS)/metabolic components and colorectal adenoma risk and quantify the dose-response association between them, aiming to provide more clues for better decision-making. METHODS We searched PubMed, EMBASE, and Cochrane Library through June 2020 for clinical studies of MetS and colorectal adenoma risk. RevMan 5.3 software and STATA 12.0 software were employed for meta-analysis. RESULTS Seventeen studies representing 44,336 participants were eligible for analysis. The overall meta-analysis showed that MetS patients had increased risk of colorectal adenoma (OR: 1.39, 95% CI 1.24-1.57; P < 0.05). Dose-response analysis presented that every increased number of Mets components was associated with a 8% increment of colorectal adenoma risk(OR: 1.08; 95% CI: 1.04-1.11). Subgroup analysis by age revealed a higher colorectal adenoma risk in MetS patients 50 years or older (OR 1.46; 95% CI 1.21-1.76; P<0.0001), rather than MetS patients younger than 50 years old (OR 1.23; 95% CI 0.95-1.59; P = 0.11).When stratified by sex, the analysis revealed a higher risk of colorectal adenoma in male MetS patients (OR 1.32; 95% CI 1.15-1.53; P = 0.0001), rather than females (OR 1.65; 95% CI 0.90-3.02; P = 0.10)(Figure 5B). The analysis split by adenoma location showed that the right colon (OR 1.35; 95% CI 1.04-1.75; P = 0.03), instead of the left colon (OR 1.16; 95% CI 0.84-1.78; P = 0.37) or rectum(OR 1.26; 95% CI 0.89-1.46; P = 0.20), was the predilection site associated with increased colorectal adenoma risk in MetS patients. CONCLUSIONS Overall, our meta-analysis showed that MetS was associated with a higher risk of colorectal adenoma. MetS patients, especially old (≥50 years) male patients, should be a risk population for colorectal adenoma screening so that they can benefit from behavioural interventions that can help prevent the development of colorectal cancer.