Fig. 1

Flowchart of the selection process for the target group. A total of 2922 subjects were selected from the Niigata City Medical Association database, of which 563 patients were not within the target age for the analysis. Based on the ascertainment by local cancer registry or pathology reports which were collected from hospitals and clinics, 2357 patients were verified to have gastric cancer and 40 patients who had a history of gastric cancer before being registered as having cancer. To investigate the optimal screening interval in each screening, individuals who had different screening histories were excluded. Excluding those who had diffrent screening histories, the patients in whom gastric cancer was detected by gastric cancer screening were divided into 2 groups: endoscopic screening group (n = 1585) and radiographic screening group (n = 462)