[Significance of the lamina muscularis mucosae of the stomach in invasiveness of gastric cancer].

Gastric carcinoma in the fundic gland area has a greater tendency to submucosal invasion than that in the pyloric gland area. In order to clarify the reason for this phenemenon, we investigated the thickness and structure of the lamina muscularis mucosae (LMM) of both the fundic and pyloric areas, using 15 subtotally resected stomachs. The average thickness of the LMM of the fundic and pyloric gland areas was 56 microns and 104 microns, respectively, the former being significantly thinner than the latter. On the contrary, no remarkable difference was seen between the two areas in the roughness of the mesh pattern made up of interlacing smooth muscle fibers. These findings suggest that the more likely occurrence of submucosal invasion of carcinoma in the fundic gland area is attributable to the distinct thinness of the LMM in that area through which the mucosal carcinoma invades the submucosal layer.