Multicenter study of invasive gastric cancer detected after 10 years of Helicobacter pylori eradication in Japan: Clinical, endoscopic, and histopathologic characteristics

Abstract Objectives Gastric cancer can be diagnosed even in patients long after Helicobacter pylori eradication. Most cases involve intramucosal lesions; however, some are invasive and require surgery. To clarify appropriate long‐term surveillance methods, this study compared invasive gastric cancer diagnosed ≥10 and <10 years after eradication. Methods This retrospective multicenter study included 14 institutions. We included 377 patients with gastric cancer with submucosal or deep invasion after surgical or endoscopic resection. Ordered logistic regression analysis was used to explore the factors contributing to the pathological stage and histological type. Results Invasive gastric cancer was detected in 84 patients (Group L) and 293 patients (Group S) ≥10 and <10 years after H. pylori eradication, respectively. Endoscopic mucosal atrophy at the time of cancer detection was similar in both groups; 50% of the patients had severe atrophy. Annual endoscopy correlated with early pathological stage (odds ratio OR 0.28, 95% confidence interval CI 0.14–0.54, p < 0.001). Group L exhibited an independent correlation with the advanced pathological stage (OR 2.27, 95% CI 1.06–4.88, p = 0.035) and the undifferentiated type (OR 2.12, 95% CI 1.16–3.90, p = 0.015). The pure differentiated type and early pathological stage significantly ( p = 0.001) correlated with severe mucosal atrophy in Group S but not in Group L. Conclusions Invasive cancers diagnosed ≥10 years after H. pylori eradication were likely to be more malignant in histological type and pathological stage. Gastric cancer surveillance should continue regardless of endoscopic atrophy, particularly ≥10 years after eradication.