Intestinalization of gastric signet ring cell carcinomas with progression.

Recent developments in mucin histochemistry and immunohistochemistry have made reliable determination of the gastric and intestinal phenotypes of gastric carcinoma cells possible. Phenotypic expression changes from gastric epithelial cell type to intestinal epithelial cell type with the growth of gastric tumours in experimental animals. We studied cell differentiation in gastric signet ring cell carcinomas with progression in 203 surgically obtained specimens. The results showed that the proportion of gastric phenotype carcinomas, in which over 90% of the tissue consists of gastric epithelial cell type cells, decreases with the depth of invasion. The proportion of mixed phenotype carcinomas (between 10% and 90% of the tissue made up of gastric and/or intestinal epithelial cell type cells) increases. The intestinal phenotype (over 90% intestinal epithelial cell type carcinoma cells) was found in four carcinomas (about 2%) involving the serosa. No clear relationship was evident between phenotypic expression of carcinoma cells and the degree of intestinal metaplasia of the surrounding mucosa. Progression of gastric signet ring cell carcinomas is associated with a phenotypic shift from gastric to intestinal type expression.

Sialosyl-Tn antigen as a marker of gastric cancer progression: an international study.

Sialosyl-Tn, a mucin-associated carbohydrate antigen, is not expressed by normal mucus-producing cells of the stomach but becomes expressed in metaplastic, pre-malignant and malignant gastric tissues. Reports vary as to the frequency of STn expression and its prognostic role in gastric cancer. To determine whether these differences might be due to inter-country variations in gastric cancer biology, we immunohistochemically analyzed 340 gastric cancers from 2 countries at high-risk (high incidence) for gastric cancer (Japan and Chile), one with intermediate risk (Brazil) and one with low-risk (USA). Expression of STn was correlated with clinico-pathological features of the tumors and with cancer-related survival. Regardless of country, the frequency of STn-positive tumors was lower in non-invasive ("early") than in advanced gastric cancer. Consequently, high-risk countries where early gastric cancer is more common demonstrated a lower overall frequency of STn-positive tumors. In all 4 countries, STn expression directly correlated with depth of invasion, stage, and lymph node involvement. In addition, STn expression correlated with a poor prognosis in all 4 countries, but the effect of STn on survival was not independent of tumor stage. Our findings indicate the need to consider the inherent gastric cancer risk and prevalence of early gastric cancer in the study population when reporting frequency of STn expression in gastric cancer. Regardless of country, however, STn expression is a marker of gastric cancer progression suggesting that cancer-associated mucins play a role in the malignant behavior of this tumor.