Hepatocellular carcinoma and other complications of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in Japan: A structured review of published works.

Aims: Hepatocellular carcinoma (HCC) is a significant cause of morbidity and mortality in Japan. As the treatment of viral hepatitis improves, non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are rapidly becoming leading causes of HCC in Japan. This structured review aims to characterize the morbidity and mortality of HCC and other malignant and non-malignant complications among Japanese NAFLD and NASH patients.

Methods: An English and Japanese structured search of published works was undertaken in PubMed, Embase, and Ichushi Web databases, identifying 6553 studies, 34 of which met predefined inclusion criteria.

Results: Hepatocellular carcinoma was the most common incident malignancy among NAFLD/NASH patients, with higher incidence in patients with advanced/severe fibrosis (F3/F4) of 10.5%-20.0%. Although NASH results in a lower HCC cumulative incidence than hepatitis C virus (HCV) (11.3% vs. 30.5%), they have similar impacts on health outcomes, including overall mortality. Among Japanese NASH patients, HCC was found to be the main driver of mortality (40.0% in 2.7 years in NASH-HCC). With longer follow-up, higher mortality rates are observed in F3/4 patients: 25.0% in NASH F3/F4 versus 0.0% in NASH F0/2 over 7.7 years. The NASH-HCC patients also have a higher post-operative mortality than HCV-HCC patients. Additionally, NAFLD/NASH patients had higher rates of cardiovascular disease than non-NAFLD/NASH controls, and slightly higher rates of gastric cancer than HCV patients.

Conclusion: Hepatocellular carcinoma is the most common malignancy and cause of death among NAFLD/NASH patients in Japan, with higher mortality observed among those with advanced disease and complications. Early identification and effective treatments are needed.