The study was conducted at Fukuoka University from January 2009 to January 2018. The Medical Ethics Committee of Fukuoka University approved this study (IRB number: U20-01-011).
The primary endpoint of this study was to investigate the association between the clinicopathological characteristics and endoscopic features of EGCs diagnosed after H. pylori eradication. We enrolled 397 consecutive patients who underwent endoscopic submucosal dissection (ESD) of their EGC. Two hundred and twenty-five patients were excluded. The remaining 172 patients were divided into two groups. The H. pylori-eradication group (H. pylori-EG) comprised 36 EGCs in 32 patients who had undergone H. pylori eradication therapy >1 year before. The H. pylori-positive group (H. pylori-PG; control group) comprised 156 EGCs in 140 patients with active H. pylori infection. In both groups, EGC was treated by ESD (Fig. 1).
It remains unclear whether the degree of mucosal atrophy affects the characteristics of EGC after eradication of H. pylori. Therefore, we compared the clinicopathological characteristics and endoscopic features between the two groups classified by the degree of gastric mucosal atrophy in the H. pylori-EG. We investigated the association between EGC characteristics and the degree of mucosal atrophy after H. pylori eradication. Twenty-nine EGC lesions, in which the degree of mucosal atrophy had been confirmed in ESD specimens, were divided into two subgroups according to endoscopic and histological examinations. These subgroups included the mild atrophic mucosa subgroup exhibiting no to mild atrophic mucosa around the EGC, and the moderate to severe atrophic mucosa subgroup displaying moderate to severe atrophic mucosa around the EGC (Fig. 1).
Evaluation of H. pylori status
Evaluation of H. pylori eradication treatment was based on the 13C-urea breath test (UBT) or serum immunoglobulin (Ig) G antibody test (E-plate, Eiken, Tokyo, Japan) and on histological assessment with Giemsa stain using endoscopic biopsy specimens. When both examinations were negative, we determined that H. pylori had been eradicated [4-6]. One hundred and forty patients in the control group were H. pylori-positive based on 13C-UBT or serum IgG antibody and on histological assessment with Giemsa stain, and had no history of receiving H. pylori eradication therapy.
Clinicopathological findings such as tumor size, location, macroscopic type, histological type, and depth of invasion were reviewed for gastric carcinomas according to both the Japanese  and World Health Organization classifications . The extent and degree of atrophic gastritis was evaluated endoscopically and histologically and classified into six categories according to the Kimura and Takemoto classification system (C-1 to O-3) .
Endoscopic examinations were performed by three experienced endoscopists (H.I, T.T, and N.K) using a magnifying endoscope (GIF-H260Z, H290Z, Olympus Medical Systems, Tokyo, Japan). We used structural enhancement levels of A-8 for conventional endoscopy and B-8 for narrow-band imaging with magnifying endoscopy (NBI-ME). NBI-ME for diagnosing EGC was performed using a systematic classification system based on microvascular and microsurface patterns (the “VS classification”). An irregular microvascular pattern and/or an irregular microsurface pattern with clear demarcation lines are the hallmarks of EGC . EGCs were confirmed using histopathological findings of biopsies and ESD samples.
Data were analyzed using JMP® 15 statistical software (SAS Institute Inc., Cary, NC, USA). Continuous variables between two groups were evaluated using the Mann–Whitney U test. Categorical variables were evaluated using the chi-squared test. P values <0.05 were considered statistically significant.