Characteristics of Magnifying Endoscopy with Narrow Band Imaging Findings in Gastric Cancer after <italic>Helicobacter pylori</italic> Eradication.

[BACKGROUND] Helicobacter pylori (H. pylori) eradication reduces the risk of gastric cancer development and is effective in patients with chronic atrophic gastritis. Recently, an increase in gastric cancer incidence has been observed in daily clinical practice in patients who have undergone H. pylori eradication. Therefore, continuous surveillance endoscopy is important for detecting gastric cancer after H. pylori eradication. In addition, endoscopic findings may differ between non-eradication and post-eradication gastric cancer. Magnifying endoscopy with narrow band imaging (ME-NBI) has been useful for the diagnosis of post-eradication gastric cancer, regardless of the histological type. However, there have been no comprehensive reports in this regard. Here, we aimed to clarify the characteristics of ME-NBI findings in gastric cancer following H. pylori eradication.

[SUMMARY] In differentiated- and mixed-type cancers (a mixture of differentiated and undifferentiated type), the cancer may be covered by noncancerous epithelium following H. pylori eradication; however, abnormalities can still be detected using ME-NBI. Therefore, ME-NBI is suitable for the diagnosis of post-eradication gastric cancer. In undifferentiated-type cancer, ME-NBI is more useful in diagnosing post-eradication gastric cancer than non-eradicated gastric cancer because of the clear contrast between cancerous and noncancerous areas following eradication. In addition, when non-eradicated gastric cancer is detected, rather than performing endoscopic submucosal dissection (ESD) or gastrectomy without eradication, it is beneficial to start patients on eradication therapy immediately and diagnose the disease extent with ME-NBI without awaiting the results of the eradication assessment and performing ESD or gastrectomy. This approach is expected to prevent misdiagnosis of the tumor size and reduce the positivity of the horizontal margin in ESD or gastrectomy.

[KEY MESSAGES] The number of post-eradication gastric cancer cases is expected to increase in comparison to non-eradicated gastric cancer cases, as H. pylori eradication is being widely used in chronic atrophic gastritis cases. Therefore, the diagnosis of post-eradication gastric cancer using ME-NBI is expected to gain importance in daily clinical practice.