Gastric-type adenocarcinomas in the stomach

Gastric carcinomas are classified histogenetically into diffuse and differe ntiated types. The latter are often referred to as intestinal-type carcinom as and are believed to originate from intestinal metaplasia. However, histo genetic studies on smaller and initial lesions of the differentiated adenoc arcinoma do not support this. From phenotypical expression of neoplastic le sions arising in hyperplastic polyps of the stomach we first proposed an en tity of gastric-type adenocarcinomas, which has been widely accepted. Our r ecent mucin and immunohistochemical investigations reveal that most smaller adenocarcinomas retain gastric-type differentiation and that those of the exclusively intestinal phenotype are rather rare. On the other hand, most a denomas are strongly and extensively positive for intestinal marker, indica ting that the adenoma-carcinoma sequence is not a common event in the stoma ch carcinogenesis. Other studies show that the expression of intestinal muc in or carbohydrate antigen as expressed in intestinal metaplasia is manifes ted more extensively in carcinoma cells in larger tumors. It is suggested t hat intestinalization of tumor cells is a time-dependent phenomenon. Differ ential gene abnormalities between gastric and intestinal-type carcinomas of the stomach are discussed, regarding their histogenesis and progression.