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.