Impact of nonalcoholic fatty liver disease on the risk of metachronous colorectal neoplasia after polypectomy

Background/Aims Metabolic syndrome has been reported to be a risk factor for metachronous colorectal neoplasia (CRN). However, the impact of nonalcoholic fatty liver disease (NAFLD), a hepatic manifestation of metabolic syndrome, on the development of metachronous CRN after polypectomy has been rarely examined. We evaluated the association between NAFLD and the development of metachronous CRN after polypectomy. Methods Asymptomatic subjects who underwent abdominal ultrasonography and endoscopic removal of ≥ 1 adenomas at the index colonoscopy between 2010 and 2014, and had a follow-up surveillance colonoscopy until 2017 were analyzed. Results Of 6,182 participants, 2,642 (42.7%) had NAFLD at the time of the index colonoscopy. Patients with NAFLD had significantly higher cumulative incidence rates of metachronous overall CRN than those without NAFLD in both men (19.4% vs. 18.2% at 3 years and 49.2% vs. 44.0% at 5 years; p = 0.001) and women (18.7% vs. 10.5% at 3 years and 56.1% vs. 29.8% at 5 years; p < 0.001). Even after adjusting for confounders, NAFLD remained independently associated with an increased risk of metachronous overall CRN in both men (adjusted hazard ratio [HR], 1.17; 95% confidence interval [CI], 1.06 to 1.29) and women (adjusted HR, 1.63; 95% CI, 1.27 to 2.07). Additionally, NAFLD was an independent risk factor for metachronous advanced CRN (ACRN) in women (adjusted HR, 2.61; 95% CI, 1.27 to 5.37). Conclusions NAFLD is related to an increased risk of metachronous CRN after polypectomy. Especially, women with NAFLD are at an increased risk of developing metachronous ACRN. Our results indicate a possible effect of NAFLD on the pathogenesis of CRN