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.

Background: Gastric cancer is a common malignancy with a high incidence in East Asia. Gastric resection ranges from endoscopic resection to open total gastrectomy. However, nationwide data are lacking.

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 types of resection performed for malignant gastric tumors between 2014 and 2021, patients' age and sex distributions, 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 that of total gastrectomies 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 were aged ≥ 65 years. The annual incidence of gastric resection per million population was highest in Tottori (n = 1236) 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 open total gastrectomy. However, regional disparities remain in resection type. Standardization of treatment and a more even distribution of specialists are needed.