Special features of intestinal metaplasia and its relation to early gastric carcinoma in man: observation by a method in which leucine aminopeptidase activity is used.

The degree of intestinal metaplasia and its macroscopic distribution in gastric mucosa were examined by a new method in which leucine aminopeptidase (LAP) activity is used to investigate the relationship between intestinal metaplasia and gastric carcinoma. Since LAP is a specific enzyme of intestinal metaplasia, the area showing positive reaction for this enzyme corresponds strictly with the zone of intestinal metaplasia examined microscopically. Almost all metaplasia was demonstrated by this method. This method was used to examine 40 human gastric carcinomas confined to the mucosa. Gastric mucosa containing differentiated tubular-type carcinoma (60%) was associated with a high degree of metaplasia in comparison with the low degree of metaplasia in poorly differentiated carcinoma (40%). Differentiated tubular-type carcinoma was closely related to intestinal metaplasia. However, all carcinomas arising from the mucosa without intestinal metaplasia (18%) were poorly differentiated. Therefore, gastric carcinomas occurring in Japanese patients are frequently and closely related to intestinal metaplasias.