Hepatocarcinogenesis in non-alcoholic fatty liver disease in Japan

In Japan, there has been a gradual increase in cases of non-viral chronic liver diseases, including non-alcoholic fatty liver disease (NAFLD), occurring with hepatocellular carcinoma (HCC). First, a national survey investigating the etiology of HCC in Japan was performed. Among HCCs based on non-viral disease, alcoholic liver disease with HCC accounted for 7.2% of all HCCs, followed by chronic liver disease of unknown etiology with HCC (5.1%) and NAFLD with HCC (2.0%). The clinical characteristics of these three HCC groups were clearly different. In our second analysis, the HCC development rates among liver cirrhosis with NAFLD, alcoholic cirrhosis, and cirrhosis with hepatitis C virus (HCV) were compared. HCC development rates were 11.3%/5 years in NAFLD cirrhosis, 30.5%/5 years in HCV cirrhosis, and 12.5%/5 years in alcoholic cirrhosis, suggesting that the hepatocarcinogenesis in NAFLD and alcoholic liver disease were similar but were lower than that in HCV. Using Cox hazards analysis, older age, higher serum γ-glutamyl transpeptidase level, and higher Child-Pugh score as risk factors of HCC were identified. Finally, clinical data of NAFLD-HCC with the data for HCC with HCV (HCV-HCC) were compared. The percentage of NAFLD-HCC patients with des-gamma-carboxy prothrombin-positive was higher than that with α-fetoprotein-positive. The 5-year survival and recurrence rates for NAFLD-HCC were almost similar to those for HCV-HCC. In Asian countries, the prevalence of NAFLD is increasing. Therefore, elucidating the pathogenesis and clinical features of HCC in patients with NAFLD is indeed an urgent problem.