Relationship between immunoexpression of mucin peptide cores MUC1 and MUC2 and Lauren's histologic subtypes of gastric carcinomas

Laurèn's system subdivides gastric cancers into an intestinal type and a diffuse type. This histological classification mirrors histogenetic hypotheses according to which the intestinal-type cancer derives from intestinal metaplasia and dysplasia, while the diffuse-type originates directly from gastric mucosa, with or without a preceding non-metaplastic dysplasia. Studies concerning mucins expression in gastric neoplastic and preneoplastic lesions have provided contradictory data concerning such histogenetic relationships. The aim of the present study was to verify whether a correlation between mucins phenotype and Lauren's classification subsists. 40 gastric adenocarcinomas, subdivided, according to Laurèn's classification, into 27 intestinal-type, 10 diffuse-type and 3 unclassified cases, were examined for MUC1 and MUC2 immunohistochemical expression. Intestinal-type carcinomas displayed a MUC1-positive staining in 23/27 cases and a MUC2-positive immunoreaction in 10/27 cases. Diffuse-type carcinomas expressed MUC1 in 3/10 and MUC2 in 8/10 cases, respectively. According to the mucins expression pattern, three phenotypes were identified: the gastric phenotype (MUC1+/MUC2-); the gastro-intestinal phenotype (MUC1+/MUC2+) and the intestinal phenotype (MUC1-/MUC2+). The gastric phenotype was significantly higherin intestinal-type adenocarcinomas, whereas cases showing an intestinal phenotype were significantly more frequent in diffuse-type adenocarcinomas. These findings provide evidence for a lack of correlation between Lauren's classification and MUC1 and MUC2 phenotypes. In particular, the term intestinal-type tumour as referred to gland-forming gastric cancer does not seem to reflect an immunohistochemical phenotype.