Fig. 1

Flow chart for target group selection. In a large-scale cohort study conducted in Japan (i.e., Japan Public Health Center Study [JPHC study]), a population-based cohort of 61,009 men and 62,567 women was identified and followed from January 1, 1990 to December 31, 2004. Of 97,644 eligible subjects in the JPHC study cohort, 13,467 men and 23,278 women who donated blood samples at baseline were included. Cases of gastric cancer were extracted from the cancer registry for the JPHC study based on site. Among 1,681 cases with a histologically proven diagnosis made from 1990 to 2004, plasma at baseline was obtained from 512 cases. One case with a technical error of H. pylori antibody measurement and the matched control were excluded. The dataset included 511 case subjects and 511 matched control subjects. For this analysis, 14 case subjects who were diagnosed as having gastric cancer before the blood donation date and 14 matched control subjects were excluded. Thus, a total of 994 subjects (497 case subjects having gastric cancer and 497 healthy control subjects) were used for the ROC analysis in this study