HISTOGENESIS AND CHARACTERISTICS OF GASTRIC-TYPE ADENOCARCINOMAS IN THE STOMACH

The characteristics and histogenesis of gastric-type adenocarcinomas w ere studied for endoscopically removed hyperplastic polyps and intramu cosal cancers found in surgically resected stomachs (m-cancers). Among 421 hyperplastic polyps, 14 differentiated-type carcinomas were found (HP-cancers). Eleven (78.6%) of these lesions were gastric-type adeno carcinomas. Out of 65 m-cancers, 22 were undifferentiated-type carcino mas and 43 were differentiated-type carcinomas, the latter being class ified into 10 gastric-type adenocarcinomas (23.2%) and 13 intestinal-t ype adenocarcinomas: the remaining 20 were of mixed gastric and intest inal type. The mean age of the gastric-type adenocarcinoma patients di d not differ from that of patients with other differentiated-type carc inomas. No appreciable signs of intestinal metaplasia were noted in HP -cancer polyps. In m-cancers, the degree of intestinal metaplasia of t he surrounding mucosa of gastric-type adenocarcinomas tended to be low er than in the other differentiated-type carcinomas, indicating a weak relationship between the histogenesis of gastric-type adenocarcinomas and intestinal metaplasia. Studies by PCNA (proliferating cell nuclea r antigen) immunohistochemistry, showed that in over half of the gastr ic-type adenocarcinoma cases PCNA-positive cells tended to be localize d within tumor tissues. In addition, point mutations of the c-Ki-ras g ene were detected in 1 gastric-type adenocarcinoma and 2 intestinal-ty pe adenocarcinomas, suggesting the occurence of a common genetic abnor mality.