Expression and Prognostic Significance of EpCAM

AIM: EpCAM (CD326) is a transmembrane glycoprotein on epithelial cells. To assess its expression, an increasing number of commercially available antibodies combined with multiple staining protocols with varying sensitivities and specificities are in use. There is no consensus about definition of positivity. Systematic and reliable comparison of results is therefore hampered. To maximise the reproducibility of the results, we investigated EpCAM expression on tissue microarrays. METHODS: The murine monoclonal antibody ESA (clone VU-1D9) was used at a dilution of 1:800 after antigen retrieval by microwave at 80 degree C for 30 min. Tissue microarrays containing gastrointestinal carcinoids (n = 91) and endometrial (n = 316) and esophageal (n = 54) carcinomas were analysed and the results were compared with clinicopathological features. RESULTS: In gastrointestinal carcinoids, 87% of cases had strong EpCAM expression, and less than 2% were completely EpCAM-negative. This EpCAM expression was not associated with tumor localization within the gastrointestinal tract. All endometrial and esophageal carcinomas expressed EpCAM to some extent, but there was no correlation of EpCAM expression with histological grade, tumor stage or patient survival in the uterus and esophageal cancers. CONCLUSION: EpCAM was frequently expressed in adenocarcinomas of the uterus, esophageal squamous cell carcinomas and gastrointestinal carcinoids. This high frequency makes these tumors as potential targets of anti-EpCAM therapies and may render individual testing before application of the therapy unnecessary.