A novel gastric-cancer-associated mucin antigen defined by a monoclonal antibody A3D4

Immunohistochemical biomarkers of value in distinguishing primary ovarian carcinoma from gastric carcinoma: a systematic review with statistical meta-analysis

AIMS

To compare the relative risk of antigen expression being detected immunohistochemically in ovarian and gastric carcinoma aggregated from studies performed for diagnostic purposes, with the relative risks of their expression in all patients in the English literature.

METHODS AND RESULTS

Both types of series indicated that cytokeratin (CK) 7 expression was greater and that of CK20 and carcinoembryonic antigen less in ovarian than in gastric carcinoma (P < 0.05). Synthesis of all data available for MUC-2 suggested it was more commonly expressed in ovarian carcinoma, whereas the relative risk in papers that directly compared its expression suggested that it was more common in the gastric carcinoma (P = 0.2, NS). Aggregating all possible data suggested villin was more likely to be expressed in ovarian cancers, whereas studies in which its expression was compared directly in both tumours suggested the opposite. Although statistically significant, patient numbers were small.

CONCLUSION

Provided sufficient numbers of cases are studied, analysis of studies comparing antigen expression for diagnostic purposes in tumours from two body sites is likely to be supported in the wider literature. The design of such comparative studies is informed by aggregating data from single tumour studies.

Mucin phenotype and microsatellite instability in early multiple gastric cancers

Clinicopathologically, multiple gastric cancers (MGCs) are reported to involve predominantly intestinal-type adenocarcinoma and frequently to be associated with severe intestinal metaplasia. However, there are few reports concerning the characteristic biomarkers of early MGCs. The aim of our study was to identify the cellular lineage defined by mucin phenotypes and the relationships among mucin phenotypes, background mucosa and microsatellite instability (MSI) of early MGCs. We examined mucin phenotypes of 63 surgically resected carcinomas from 25 patients with early MGCs and 39 early solitary gastric cancers (SGCs) by immunohistochemical analysis using a panel of monoclonal antibodies. MSI and the degree of intestinal metaplasia (IM) on the background mucosa were also examined. In early MGCs, the incidence of cancer exhibiting the gastric phenotype (G-type) was 59% (37 of 63 cancers), which was higher than that in early SGCs (23%, 9 of 39 cancers). There was a significant difference between the distributions of mucin phenotypes in early MGCs and early SGCs (p = 0.001). Whereas half of the G-type cancers in early MGCs were related to severe IM, none of the G-type cancers in early SGCs were related to severe IM. In the early MGCs, MSI was observed in 21 of 63 cancers (33.3%). In contrast, MSI was observed in only 3 of the 39 (7.7%) early SGCs, indicating a significant difference between these 2 groups (p < 0.01). Our results suggest that the characteristic features of early MGCs are the gastric mucin dominant phenotype and high frequency of MSI.

Decreased expression of the metastasis suppressor gene KAI1 in gastric cancer

KAI1 was immunohistochemically detected in the lower part of fundic glands and intestinal metaplasia in non-cancerous gastric tissues, while only 11.0% (8/73) of cancerous tissues were shown to be positive. The relationship between various clinicopathological characteristics of patients with gastric cancer and KAI1 expression in their tumors was then analyzed to reveal that the incidence of positivity was 16.6% (8/48) of patients with stage Ia-IIIa and 0% (0/25) of patients with stage IIIb-IVb (P < 0.05) and that the incidence of peritoneal or hepatic metastasis tended to be lower in KAI1-positive tumors than in negative ones. These results suggest that decreased KAI1 expression may be related to the progression of gastric cancer.