Epithelial cell adhesion molecule (EpCAM) has been used as diagnostic/prognostic marker and therapeutic target. The aim of the present study was to compare immunoreactivity of antibodies against distinct epitopes in the ectodomain of EpCAM for detection of carcinoma from different primary sites and of different histological types in effusions and peritoneal wash. Two antibodies against epitopes in the EGF-like domain I (clones Moc-31 and Ber-EP4) and one antibody against the epitope in the cysteine-poor region (158210) of EpCAM were used (all commercially available). Independently of the clone used, EpCAM overexpression was observed in almost all samples when all the adenocarcinoma samples were analyzed together. By using Moc-31, EpCAM overexpression was observed in all samples of adenocarcinoma. Absence of EpCAM overexpression was observed in a few adenocarcinoma samples at some sites of tumor origin, including ovary, breast and stomach, when Ber-EP4 and 158210 were used. Regarding carcinomas aside from adenocarcinomas, histological types, such as squamous cell, urothelial and small cell carcinoma showed different degrees of EpCAM expression according to the antibody used. In squamous cell carcinoma, overexpression was observed only with the clone 158210. It was concluded that, overall, most samples of metastatic carcinoma from effusions showed overexpression of EpCAM. However, there are significant variations in its detection according to the primary site, histological type of the carcinoma and depending on the antibody used. Thus, the use of more than one type of anti-EpCAM antibody would increase the chance of its detection in metastatic carcinoma effusion.
Keywords: cancer; carcinoma; cytology; effusions; epithelial cell adhesion molecule; immunocytochemistry.