[New concepts on precancerous lesions of the stomach]

As for precancerous lesion of the stomach detail analysis of endoscopic follow-up cases and histopathological investigations brought some new informations on its carcinogenesis. In this paper recent several reports were introduced and discussed on new opinion of precancerous conditions such as adenoma, intestinal metaplasia, gastric ulcer, remnant stomach and H. pylori. Gastric adenoma was considered to be neoplastic because of high incidence of carcinoma in situ. The stomach coexisted with adenoma showed high percentage of new arising tumor in same stomach and therefore, we can say that these are thought to be high risk group for well differentiated adenocarcinoma. Concerning the relation between intestinal metaplasia and gastric cancer we have never obtained final conclusion. However, it is likely that incomplete type of intestinal metaplasia appeared to be coexistent with gastric cancer, especially intestinal type carcinoma, which was thought to be paracancerous lesions. Recent advance of molecular biology has indicated new knowledge on gastric carcinogenesis, suggestive of multistep pathways. According to their reports, genomic instanbility appeared frequently in gastric adenoma and intestinal metaplasia as well as gastric carcinoma. Gastric carcinogenesis for ulcer, remnant stomach and H. pylori was also discussed. In near future the mechanism of gastric carcinogenesis is expected to be solved from view point of genetic events.