Clinical epidemiology of the endoscopic, laparoscopic, and surgical resection of malignant gastric tumors in Japan, 2014-2021: a retrospective study using open data from a national claims database

ABSTRACT Background Gastric cancer is one of the most common malignancies and its incidence is high in East Asia. Several options are available for resection of malignant gastric tumors, ranging from endoscopic resection of early-stage cancer to open total gastrectomy. However, there has been a lack of nationwide data on gastric resection in Japan. Methods This observational study analyzed data from the publicly accessible National Database of Health Insurance Claims and Specific Health Checkups, which includes most national health insurance claims data in Japan. Trends in the various types of resection performed for malignant gastric tumors between 2014 and 2021, the age and sex distributions of patients undergoing these procedures, and regional disparities were investigated. Results The annual number of resections was highest in 2015 (109,000) and lowest in 2020 (90,000) after the COVID-19 pandemic. The proportion of endoscopic resections increased from 47% in 2014 to 57% in 2021 while the proportion of total gastrectomies performed during this period decreased from 17% to 10%. In 2021, 70% of patients who underwent resection were men. That year, 83.8% of all patients who underwent any type of gastric resection and 87.1% of those who underwent endoscopic submucosal dissection (ESD) were aged ≥65 years. The annual incidence of gastric resection per million general population was highest in Tottori (n=1,236) and lowest in Okinawa (n=251). The proportion of endoscopic resections was highest in Miyagi (66%) and lowest in Aichi (45%) and that of open surgery was highest in Aomori (36%) and lowest in Wakayama (5%). Conclusions Gastric malignancy is increasingly treated by endoscopic submucosal dissection rather than by open total gastrectomy. However, there are regional disparities in the resection methods used. Standardization of screening and treatment and a more even distribution of specialists are needed.