Expression of p53 protein as a prognostic indicator of reduced survival time in diffuse-type gastric carcinoma

To determine whether p53 expression is different in intestinal and diffuse types of gastric carcinoma, we investigated p53 immunohistochemical expression in 178 primary gastric carcinomas. Overexpression of p53 was observed in 50 out of 100 intestinal-type tumors (50.0%) and in 27 out of 78 diffuse-type tumors (34.6%). A significant difference was found in the timing of p53 overexpression between the two types of carcinomas. Overexpression of p53 occurred often in the early stage of intestinal-type tumors, and there was no significant difference in expression between early and advanced cancers. In contrast, p53 overexpression did not occur often in the early stage of diffuse-type tumors, but it increased progressively as the tumor advanced. Analysis of patient survival revealed that p53 overexpression correlates significantly with a poor prognosis in diffuse-type gastric carcinoma (P=0.003) but not in intestinal-type. Multivariate analysis showed that only pathological stage was an independent prognostic indicator. Our results suggest that p53 overexpression plays a different role in tumor carcinogenesis and progression of these two types of gastric cancers.