[Morphological studies on precancerous lesions of the stomach and large intestine]

Precancerous conditions (high cancer-risk status) in the stomach and large intestine were discussed from a histological point of view. As to the conditions for the stomach, polyps (hyperplastic polyps and atypical epithelial lesions of flatly elevated type, so-called ATP), intestinal metaplasia and chronic ulcer (including ulcer scar), and as to those for the large intestine, adenomas and mucosa with some mucous changes were selected for this study. ATP was considered to be a neoplastic lesion rather than a hyperplastic or regenerative one, appearing with a high risk for a carcinoma of well-differentiated type: the lesion showed high incidence of focal carcinoma, particularly the ones more than 2 cm in diameter. Intestinal metaplasia has been frequently observed in the Japanese and when this change is drastically taken place, a consideration should be taken as a high risk factor for a well-differentiated carcinoma. Chronic gastric ulcer does not imply by itself a precancerous condition; however, the stomachs with ulcer seem to produce a several times higher incidence of coexistent carcinomas elsewhere in the stomach compared those without ulcer. Whether or not most of the invasive carcinomas are developed from adenomas remains debatable, even though adenoma of the large intestine is commonly suggested as a precancerous condition. A de novo carcinoma making an invasive carcinoma should also be considered. An increased sialomucin production in the mucosa of the large intestine occurred in a wide range also a possible factor for existence of carcinomas. Mucin changes demonstrated by Culling et al were discussed.