Influence of Obesity and Metabolic Abnormalities on the Risk of Developing Colorectal Neoplasia

Background: Obesity and metabolic syndrome are risk factors for colorectal neoplasia (CRN). However, the association between metabolically healthy obese (MHO) or metabolically unhealthy non-obese (MUNO) status and the risk of CRN remains unclear. Aims: We aimed to elucidate the association between MHO or MUNO status and the risk of CRN. Methods: A total of 139,023 asymptomatic subjects who underwent a primary screening colonoscopy were categorized into 4 groups according to obesity and metabolic status: metabolically healthy non-obese (MHNO), MHO, MUNO, and metabolically unhealthy obese (MUO). Results: Mean participant age was 41.0 years, and the proportion of men was 65.3%. Among men, the risk of overall CRN increased in MHO (adjusted odds ratio [AOR] 1.22, 95% confidence intervals [CI] 1.12–1.33), MUNO (AOR 1.25, 95% CI 1.18–1.31), and MUO groups (AOR 1.47, 95% CI 1.40–1.54) compared with the MHNO group, whereas the risk of advanced CRN (ACRN) increased in MUNO (AOR 1.16, 95% CI 1.002–1.33) and MUO groups (AOR 1.49, 95% CI 1.31–1.70), but not in the MHO group (AOR 0.92, 95% CI 0.70–1.21). Moreover, among non-obese men, the risk of overall CRN and ACRN linearly increased with an increasing number of metabolic abnormalities. However, among women, only the MUO group had an increased risk of overall CRN (AOR 1.34, 95% CI 1.21–1.47) and no other significant associations were observed. Conclusions: Poor metabolic health, regardless of obesity, is an independent risk factor for CRN in men. Our results suggest that men with metabolic abnormalities should be considered as a high-risk group for colorectal cancer, even if they are not obese.