Aim: The association between metabolic factors and precancerous polyps in individuals undergoing surveillance colonoscopies is unclear. We aimed to systematically summarise existing literature on the effect of various metabolic factors on the risk of precancerous polyps among these individuals.
Methods: We searched seven databases (Medline/Ovid, Cochrane Library, Web of Science, CINHAL, Scopus, PsycINFO, ProQuest) for studies published from 2010-2023. Eligible studies included cohorts undergoing surveillance colonoscopy due to a family history of colorectal cancer (CRC), or a personal history of precancerous polyps or CRC. Exposure variables included at least one metabolic factor (obesity, diabetes mellitus, hypertension, or dyslipidemia). Two independent reviewers performed article screening, data extraction, and quality assessment. The association between metabolic factors and risk of precancerous polyps was assessed using a random effect meta-analysis of pooled odds ratio (POR) or pooled hazard ratio (PHR). Heterogeneity was assessed as high when I² was >50%.
Results: 24 studies were eligible. General obesity (14 studies; POR=1.31, 95% CI 1.09; 1.57, I2=67%), central obesity (3 studies; POR=1.31, 95%CI 1.16; 1.49, I2=0%), hypertension (13 studies; POR=1.22, 95%CI 1.02; 1.44, I2=57%), high triglyceride (2 studies; POR=1.39, 95%CI 1.06; 1.83, I2=0%), and metabolic syndrome (3 studies; PHR=1.24, 95%CI 1.01; 1.51, I2=24%) were found to be a significant risk factor for precancerous polyps. For advanced precancerous polyps (tubular adenoma or sessile serrated lesions ≥10 mm in size or villous features +/- high-grade dysplasia, or any size traditional serrated adenoma), only general obesity and diabetes were eligible to assess by meta-analysis, where obesity (3 studies; PHR=3.04, 95%CI 2.01; 4.60, I2=0%) but not diabetes (3 studies; PHR=1.07, 95%CI 0.72; 1.57, I2 =0%) was significantly associated with the risk of advanced precancerous polyps.
Conclusions: Most metabolic factors were associated with precancerous polyps. Considering metabolic conditions for determining surveillance colonoscopy frequency could improve the effectiveness of CRC prevention strategies.