pS2 protein expression in gastric carcinoma. An immunohistochemical and immunoradiometric study

The aim of this study was to examine the prevalence of pS2 expression in gastric carcinoma and to determine its prognostic significance. We analysed pS2 protein expression in 50 gastric carcinomas and respective adjacent mucosas by immunohistochemistry and immunoradiometric assay (IRMA). pS2 was consistently expressed in superficial and foveolar epithelium of non-neoplastic mucosa and in 66.0% of the carcinomas. pS2 immunoreactivity was significantly higher in diffuse than in intestinal carcinomas, and in those cases with nodal metastases than in those without. No correlation was found between pS2 immunostaining and gender, age, staging, depth of wall penetration, venous invasion, ploidy and S-phase fraction. The mean levels of pS2 (IRMA) were significantly lower in gastric carcinomas than in non-neoplastic mucosas, and were not correlated with any of the aforementioned clinicopathological features. The survival of patients with pS2-positive tumours was not significantly different from that of patients with pS2-negative tumours. We conclude that pS2 expression, which can be used as a marker of gastric-type differentiation, is associated with gastric carcinoma of diffuse type. The lack of correlation between pS2 expression and most features of tumor aggressiveness and patients' survival precludes its use as a prognostic tool in gastric carcinoma.