Mode of Extension of Gastric Cancer Viewed from Intramucosal Dimensions of Early Lesions

Abstract

The mode of carcinogenesis and rate of intramucosal extension of gastric cancer were approached biometrically by measuring surface areas of early cancer lesions by means of reconstruction of multisectional histologic specimens. A total of 236 early gastric cancers which were resected at the author's department was used. So-called patches (Stout) within the mucosal cancer boundaries were also measured if present. The surface areas thus measured exhibited a logarithmic normal distribution, which allowed for a geometric mean of areas to represent an "average" area. For a gross estimate of the growth rate the "enlargement index" for a certain group of cancers was defined as the ratio of the average area of submucosal cancers, with malignant tissues invading the submucosal layer, to that of mucosal cancers of this group. The enlargement index as well as the incidence and dimensions of patches were compared among groups of cancer specimens classified from various view points, and the results led to following suggestions: the mode of development of gastric cancer is divided into two patterns. In one case carcinogenesis occurs multicentrically in a relatively wide area, and the resulting cancer lesion shows a lesser tendency to spread horizontally in the mucosal layer. This pattern is common in cancers of the depressed type, in poorly differentiated ones, in those showing ulceration, in those not associated with intestinal metaplasia of surrounding mucosa, in those occupying a middle portion of the stomach and in those of younger patients. The other is the pattern in which carcinogenesis is restricted to a small area but cancer then extends relatively rapidly in the mucosal layer. Cancers of the elevated type, well differentiated cancers, non-ulcerating cancers, those associated with intestinal metaplasia, those occupying the pyloric antrum and those of older patients may commonly follow this pattern.