Background Gastric cancer after successful Helicobacter pylori eradication therapy is often difficult to diagnose by endoscopy because of its indistinct borderline or lack of obviously cancerous characteristics. Furthermore, it has become evident that non-neoplastic epithelium covers cancerous areas in gastric cancer after eradication. Here, we investigated these endoscopic features and their relationship to histological findings. Methods We studied 24 and 47 gastric cancers in patients who had (eradication group) and had not (control group) undergone H. pylori eradication, respectively. A gastritislike appearance revealed by conventional endoscopy was defined as a mucosal pattern with no marked difference from the surrounding non-cancerous area and that revealed by narrow-band imaging (NBI)-magnifying endoscopy (ME) as the mucosal pattern observed in H. pylori-associated atrophic gastritis. We investigated a gastritis-like appearance revealed by conventional endoscopy (A), a gastritis-like appearance at the margin (B) and within (C) the cancerous area revealed by NBI-ME, and the histological characteristics of the overlying non-neoplastic epithelium. We also evaluated the relationship between endoscopic and histological findings in the eradication group. Results Endoscopy showed that features A, B and C were significantly more frequent in the eradication group (P = 0.031, P \ 0.001, P \ 0.001, respectively). Nonneoplastic epithelium covered more than 10 % of the cancerous area more frequently in the eradication group. In the eradication group, more than 90 % of cancers showing a gastritis-like appearance had non-neoplastic epithelium extending over 10 % of the cancerous area. Conclusion Gastric cancer after successful H. pylori eradication tends to have gastritis-like features due to nonneoplastic epithelium covering the cancerous tissue.

Staging of gastritis using NBI-ME approximates that based on histology, and would be a practical alternative to the latter.

Prediction of H. pylori status using NBI-magnifying endoscopy is practical, and interobserver agreement is substantial.

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