Extended Intestinal Metaplasia. A Survey of 1392 Gastrectomies from Dwellers of the Pacific Basin

Abstract

Background: To assess the extent of gastric intestinal metaplasia (IM) in gastrectomy specimens in populations of the Pacific basin having different incidence of gastric carcinoma. Materials and Methods: One thousand three hundred and nine-two gastrectomies were investigated: 1088 had a gastric carcinoma and 304 miscellaneous gastric diseases. Twenty-one thousand three hundred and fourteen histological sections were reviewed under low-power (4X). IM was either spotty (SIM) or extended (EIM= encompassing one or more entire low-power fields/section). Widespread IM (WIM) was regarded as EIM if present in ≥5 histological sections. Results and Conclusion: The percent of gastrectomies harboring a carcinoma increased significantly with increasing age more notably in those with diffuse carcinomas (DC) than in those with intestinal carcinomas (IC). The percent of gastrectomies with EIM was significantly higher in specimens with IC than with DC, particularly among elderly patients, and in specimens from countries with a high cancer incidence. The percent of gastrectomies with WIM was higher in specimens having IC than in those having DC. Migration per se did not influence the frequency of specimens with EIM in elderly Japanese patients: Japanese migrants to Hawaii had a similarly high frequency of EIM as those dwelling in Japan. Japanese patients with a gastric carcinoma showed atypical mitoses in areas with EIM far from the tumor, suggesting that cellular mutation(s) play a role in the evolution of EIM towards gastric dysplasia and carcinoma in that ethnic group. The drawback of gastric biopsies in assessing the extent of gastric intestinal metaplasia and, thereby, estimating possible cancer risk in long-term studies has been stressed.