nakagawa mitsuru

OBJECTIVE: Helicobacter pylori eradication is expected to prevent gastric cancer. However, morphological alterations after eradication often hinder accurate diagnosis. Therefore, we evaluated endoscopic and histological changes in gastric tumors after eradication of H. pylori in a time-dependent manner. METHODS: We classified 144 cases of endoscopic submucosal dissection (ESD) of early gastric cancer into the following categories: (i) patients positive for H. pylori with no eradication history, (ii) patients positive for H. pylori who underwent ESD 2 months after eradication, (iii) patients negative for H. pylori with an eradication history of at least 6 months before ESD, and (iv) patients negative for H. pylori with an unknown history. We compared endoscopic and histological factors between the groups. RESULTS: The characteristics of cancers positive for H. pylori were exploding shape, superficial high-grade atypical epithelium, and a surface proliferating zone. H. pylori eradication induced a series of endoscopic and histological changes, including shape -depression, appearance of surface regenerative and lower-grade atypical epithelium, and a downward shift of the proliferative zone within a period as short as 2 months. CONCLUSION: H. pylori eradication rapidly causes cancer regression and leads to tumor shrinkage, diminished atypism, and shortened proliferative zone, resulting in drastic morphological changes.

Epstein-Barr virus (EBV) infection is involved in a subset of gastric carcinoma (GC) cases, and is associated with distinct clinicopathological features. The present study reports a unique case of EBV-associated early-stage GC compared with the other cases experienced in our hospital. A 72-year-old male receiving treatment for cerebral infarction underwent an esophagogastroduodenoscopy (EGD) for suspicion of gastrointestinal bleeding. EGD revealed a type 0-I protruding lesion in the lesser curvature of the upper gastric corpus. Biopsy indicated well-differentiated adenocarcinoma. As the tumor diameter was >3 cm and the thickness of the tumor suggested submucosal invasion, laparoscopic gastrectomy was performed. Histological assessment revealed polypoid growth of an intramucosal, differentiated, tubular or papillary adenocarcinoma, with dense infiltration of lymphocytes. The carcinoma crypts were found to be EBV-positive on in situ hybridization. A review of the clinicopathological features of 25 EBV-associated GCs from 20 patients treated in our hospital between 2005 and 2014 was performed. All of these tumors, except that in the current case, appeared as shallow, depressed or ulcerative lesions. Thus, the current case appears to represent an unusual growth of EBV-positive GC.

Although its prevalence is declining, gastric cancer remains a significant public health issue. The bacterium Helicobacter pylori is known to colonize the human stomach and induce chronic atrophic gastritis, intestinal metaplasia, and gastric cancer. Results using a Mongolian gerbil model revealed that H. pylori infection increased the incidence of carcinogen-induced adenocarcinoma, whereas curative treatment of H. pylori significantly lowered cancer incidence. Furthermore, some epidemiological studies have shown that eradication of H. pylori reduces the development of metachronous cancer in humans. However, other reports have warned that human cases of atrophic metaplastic gastritis are already at risk for gastric cancer development, even after eradication of these bacteria. In this article, we discuss the effectiveness of H. pylori eradication and the morphological changes that occur in gastric dysplasia/cancer lesions. We further assess the control of gastric cancer using various chemopreventive agents.