Observational Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 21, 2015; 21(27): 8408-8417
Published online Jul 21, 2015. doi: 10.3748/wjg.v21.i27.8408
Gastric mucosa in Mongolian and Japanese patients with gastric cancer and Helicobacter pylori infection
Takeshi Matsuhisa, Yoshio Yamaoka, Tomohisa Uchida, Davaadorj Duger, Battulga Adiyasuren, Oyuntsetseg Khasag, Tserentogtokh Tegshee, Byambajav Tsogt-Ochir
Takeshi Matsuhisa, Department of Gastroenterology, Tama-Nagayama University Hospital, Nippon Medical School, Tokyo 206-8512, Japan
Yoshio Yamaoka, Department of Environmental and Preventive Medicine, Oita University of Medicine, Oita 879-5593, Japan
Tomohisa Uchida, Department of Molecular Pathology, Oita University of Medicine, Oita 879-5593, Japan
Davaadorj Duger, Vice President of Mongolian National University of Medical Sciences and President of Mongolian Society of Gastroenterology, Ulaanbaatar 14210, Mongolia
Battulga Adiyasuren, Department of Endoscopy, Ulaanbaatar Songdo Hospital, Ulaanbaatar 14210, Mongolia
Oyuntsetseg Khasag, Byambajav Tsogt-Ochir, Department of Gastroenterology, Mongolian National University of Medical Sciences, Ulaanbaatar 14210, Mongolia
Tserentogtokh Tegshee, Department of Gastroenterology, Third Central State Hospital, Ulaanbaatar 16081, Mongolia
Author contributions: Matsuhisa T and Yamaoka Y contributed to study conception and design, data interpretation, and writing, editing, review, and approval of the article; Matsuhisa T, Yamaoka Y, Uchida T, Duger D, Adiyasuren B, Khasag O, Tegshee T and Tsogt-Ochir B contributed to data acquisition.
Supported by (in part) National Institutes of Health, No. DK62813; and Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, No. 24406015, No. 24659200, No. 25293104, and No. 26640114.
Institutional review board statement: This study was reviewed and approved by the ethics committees of Nippon Medical School, Tokyo, Japan; Oita University, Oita, Japan; Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia; Ulaanbaatar Songdo Hospital, Ulaanbaatar, Mongolia; and Third Central State Hospital, Ulaanbaatar, Mongolia.
Informed consent statement: All study participants, or their legal guardian, provided informed written consent prior to study enrollment.
Conflict-of-interest statement: Matsuhisa T has received research funding from Eisai Co., Ltd as a part of this study.
Data sharing statement: The technical appendix, statistical code, and dataset are available from the corresponding author at matuhisa@nms.ac.jp.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Takeshi Matsuhisa, MD, Professor, Department of Gastroenterology, Tama-Nagayama University Hospital, Nippon Medical School, Tama, Tokyo 206-8512, Japan. matuhisa@nms.ac.jp
Telephone: +81-42-3712111 Fax: +81-42-3727381
Received: January 24, 2015
Peer-review started: January 25, 2015
First decision: March 10, 2015
Revised: March 30, 2015
Accepted: May 21, 2015
Article in press: May 21, 2015
Published online: July 21, 2015
Processing time: 179 Days and 3 Hours
Abstract

AIM: To investigate the characteristics of gastric cancer and gastric mucosa in a Mongolian population by comparison with a Japanese population.

METHODS: A total of 484 Mongolian patients with gastric cancer were enrolled to study gastric cancer characteristics in Mongolians. In addition, a total of 208 Mongolian and 3205 Japanese consecutive outpatients who underwent endoscopy, had abdominal complaints, no history of gastric operation or Helicobacter pylori eradication treatment, and no use of gastric secretion inhibitors such as histamine H2-receptor antagonists or proton pump inhibitors were enrolled. This study was conducted with the approval of the ethics committees of all hospitals. The triple-site biopsy method was used for the histologic diagnosis of gastritis and H. pylori infection in all Mongolian and Japanese cases. The infection rate of H. pylori and the status of gastric mucosa in H. pylori-infected patients were compared between Mongolian and Japanese subjects. Age (± 5 years), sex, and endoscopic diagnosis were matched between the two countries.

RESULTS: Approximately 70% of Mongolian patients with gastric cancer were 50-79 years of age, and approximately half of the cancers were located in the upper part of the stomach. Histologically, 65.7% of early cancers exhibited differentiated adenocarcinoma, whereas 73.9% of advanced cancers displayed undifferentiated adenocarcinoma. The infection rate of H. pylori was higher in Mongolian than Japanese patients (75.9% vs 48.3%, P < 0.0001). When stratified by age, the prevalence was highest among young patients, and tended to decrease in patients aged 50 years or older. The anti-East-Asian CagA-specific antibody was negative in 99.4% of H. pylori-positive Mongolian patients. Chronic inflammation, neutrophil activity, glandular atrophy, and intestinal metaplasia scores were significantly lower in Mongolian compared to Japanese H. pylori-positive patients (P < 0.0001), with the exception of the intestinal metaplasia score of specimen from the greater curvature of the upper body. The type of gastritis changed from antrum-predominant gastritis to corpus-predominant gastritis with age in both populations.

CONCLUSION: Gastric cancer was located in the upper part of the stomach in half of the Mongolian patients; Mongolian patients were infected with non-East-Asian-type H. pylori.

Keywords: Chronic inflammation; Gastric cancer; Glandular atrophy; Helicobacter pylori; Intestinal metaplasia; Japanese; Mongolian; Neutrophil activity; Non-East-Asian-type strain

Core tip: Characteristics of gastric cancer and gastric mucosa in Mongolian patients were observed; approximately half of the cancers were located in the upper part of the stomach. The infection rate of Helicobacter pylori was higher in Mongolian compared to Japanese patients (75.9% vs 48.3%, P < 0.0001). Mongolian patients were infected with non-East-Asian-type H. pylori strains. Atrophic and intestinal metaplasia scores were lower in H. pylori-infected Mongolian patients compared to Japanese patients (P < 0.0001). The type of gastritis changed from antrum-predominant gastritis to corpus-predominant gastritis with age in both populations.