Clinical significance of mucin phenotype, β-catenin and matrix metalloproteinase 7 in early undifferentiated gastric carcinoma

Background: The aim of this study was to examine the clinical significance of mucin phenotypes of early undifferentiated gastric carcinoma, and to identify variables that might be used to select patients suitable for minimally invasive surgery. Methods: A total of 129 patients with early undifferentiated gastric carcinoma were studied. The mucin phenotype was determined immunohistochemically using markers for M1, apomucin (MUC) 6 and MUC2. Tumours were classified into gastric (G), intestinal, gastrointestinal (GI) or unclassified type. Undifferentiated carcinomas were classified into signet-ring cell carcinoma (SIG) and non-SIG. The immunoreactivity of matrix metalloproteinase (AIMP) 7 and beta-catenin was also investigated. Results: GI-type rumours more commonly expressed non-SIG than SIG histology. The GI phenotype was associated with a higher incidence of submucosal invasion, lymphatic invasion, NLMP-7 expression and nuclear accumulation of beta-catenin than the G type. Non-SIG histology, and the combination of GI type and nuclear accumulation of beta-catenin were independent predictors of submucosal invasion. The combination of GI type and MMP-7 expression independently predicted lymphatic invasion. MMP-7 expression correlated with lymph node metastasis.