Evaluation of the geographic distribution of patients with hepatocellular carcinoma and treatments in Japan using data from the Japanese national database

The National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB), provided by the Ministry of Health, Labour and Welfare (MHLW), is an exhaustive repository that can be used to understand the nationwide epidemiology of hepatocellular carcinoma (HCC) in Japan. This study was conducted to clarify the geographic distribution of patients with HCC and treatments performed in each region of Japan using data from the NDB. A retrospective analysis was performed to determine the number of patients diagnosed, with HCC (International Classification of Diseases, 10th edition, code C22.0), who received treatment between 2016 and 2020. Number of incidences of HCC per 100,000 individuals in each Japanese region are 76 (Hokkaido), 63 (Tohoku), 55 (Kanto), 58 (Tokai), 74 (Hokuriku), 77 (Kinki), 93 (Chugoku), 101 (Shikoku), 93 (Kyushu), and 37 (Okinawa). Transarterial embolization/transarterial chemoembolization and curative treatments, including laparoscopic liver resection (LLR), open liver resection, and radiofrequency ablation, were the most frequently performed treatments in all regions, followed by systemic therapy. The proportion of patients receiving LLR was lowest in the Shikoku region (6.7%), which also had the lowest frequency of institutions certified by the Japanese Society of Hepato-Biliary-Pancreatic Surgery (JSHBPS) relative to the number of patients with HCC. Although the incidence of HCC varies across regions in Japan, the most frequently performed treatments remain consistent nationwide. This suggests that HCC treatment practices are largely standardized, regardless of geographic location. Certification by the JSHBPS appears to play a role in patient access to LLR.