Non-alcoholic fatty liver diseases and risk of colorectal neoplasia

Background Non-alcoholic fatty liver disease (NAFLD) is associated with colorectal neoplasia. Yet, NAFLD ranges from simple steatosis to steatohepatitis with advanced fibrosis. Aim To investigate the risk of colorectal neoplasia according to the presence and severity of NAFLD. Methods A total of 26 540 asymptomatic adults who underwent same day first-time colonoscopy and abdominal ultrasonography as a health check-up programme were analysed. NAFLD was diagnosed by ultrasonography. Advanced colorectal neoplasia was defined as an invasive cancer or adenoma that was at least 10 mm in diameter, had high-grade dysplasia, or had villous histological characteristics or any combination thereof. Results NAFLD patients had a higher prevalence of any colorectal neoplasia (38.0% vs. 28.9%) and advanced colorectal neoplasia (2.8% vs. 1.9%) compared to those without NAFLD. In a multivariable model adjusted for age, sex, smoking, alcohol, body mass index, first-degree family history of colorectal cancer, aspirin use and metabolic factors, the odd ratios comparing patients with NAFLD to those without were 1.10 [95% confidence interval (CI): 1.03-1.17] for any colorectal neoplasia and 1.21 (95% CI: 0.99-1.47) for advanced colorectal neoplasia. When NAFLD patients were further stratified according to the non-invasive parameters of liver disease severity, the risk of any colorectal neoplasia or advanced colorectal neoplasia was higher for those with severe liver diseases than those with mild liver diseases. Conclusions The presence and severity of NAFLD were closely associated with any colorectal neoplasia and advanced colorectal neoplasia, suggesting that clinicians should be aware of the increased risk of colorectal neoplasia in patients with NAFLD.