Trends in Hepatocellular Carcinoma Incidences in Japan Between 1996 and 2019

Background: While the proportion of hepatocellular carcinoma (HCC) cases with non-viral etiology continues to increase in Japan, the epidemiological trends in the sex and age distribution of new HCC cases remain unclear. This study examines the epidemiological trends, including the distribution of sex, age, and disease etiology, in HCC incidence over 24 years.Methods: Data of 20,547 newly diagnosed HCC patients in 1996–2019 at 19 institutions participating in the Liver Cancer Study Group of Kyushu were analyzed in this prospective study. We divided the study period into four 6-year quarters. HCC etiology was categorized as hepatitis B virus (HBV) infection, HBV+hepatitis C virus (HCV) infection, HCV infection, and both negative (non-BC). Results: The incidences of HCC per quarter of the study period were 4,311 (21.0%), 5,505 (26.8%), 5,776 (28.1%), and 4,955 (24.1%) cases, sequentially. Overall, 14,020 (68.2%) patients were male. The number of HCC cases in patients ≤50 years, 60–69 years, 70–79 years, and ≥80 years were 3,711 (18.1%), 6,652 (32.4%), 7,448 (36.2%), and 2,736 (13.3%), respectively. The average age of newly diagnosed patients increased in each quarter. HCC was associated with HBV, HBV+HCV, and HCV infections and non-BC in 2,997 (14.6%), 187 (0.9%), and 12,019 (58.5%), and 5,344 (26.0%) cases, respectively. The number of HCV-associated cases decreased in each quarter, while that of non-BC-associated cases increased.Conclusions: HCC incidence tends to increase in the elderly and in non-BC patients; in contrast, HCC incidence due to HCV tends to decrease. In countries where HCV infection is likely the predominant cause of HCC, similar trends in HCC incidence are anticipated in the future.