Elsevier

Human Pathology

Volume 35, Issue 1, January 2004, Pages 122-128
Human Pathology

Original contribution
Frequent EpCam protein expression in human carcinomas

https://doi.org/10.1016/j.humpath.2003.08.026Get rights and content

Abstract

Expression of the transmembrane glycoprotein EpCam (epithelial cellular adhesion molecule) occurs in normal epithelium of different organs and was described in carcinomas of various sites. Specific anti-EpCam therapies are now being used in clinical trials. Thus, it is of interest to know which tumor types express or overexpress this protein, and in what frequency. We therefore analyzed EpCam expression by immunohistochemistry on a tissue microarray containing 3900 tissue samples of 134 different histological tumor types and subtypes. EpCam expression was detected in 98 of 131 tumor categories. At least a weak EpCam expression in >10% of tumors was observed in 87 of 131 different tumor categories. Adenocarcinomas of the colon (81%) and pancreas (78%), as well as hormone-refractory adenocarcinomas of the prostate (71%), were identified as particularly promising therapy targets with a high fraction of strongly positive tumors. Most soft-tissue tumors and all lymphomas were EpCam negative. It is concluded that anti-EpCam therapies, if proven to be successful, will have broad applications in a wide variety of carcinomas.

Section snippets

Tumors

Tissue probes were sampled from the archives of the Institute of Pathology of the University of Basel. All relevant patient data were completely anonymized and blinded. Tumors were sampled without recording the grade, but different grades were sampled in a representatively distributed way. Finally, a total of 3912 samples, including 3557 primary tumors from 131 different tumor types and subtypes, as well as 355 samples from 30 different reference tissues, was brought into a TMA format as

Overall findings of the MTA

Of 3912 samples, 3680 (94%) could be analyzed. Reasons for noninformative spots included a lack of tumor cells in arrayed tissue (n = 114) or missing tissue (“empty spots”, n = 118). Staining was predominantly membranous, but some cytoplasmic staining also could be seen in cases with strong staining intensity. Cytoplasmic staining alone was considered to be nonspecific.

Reference tissue

Cell types with detectable EpCam expression are shown in Table 1. Mesenchymal tissue was always negative. Completely

Discussion

A total of 3680 tissue samples from 131 different tumor types and subtypes and 30 different reference tissues was immunohistochemically analyzed for EpCam expression by using TMA technology. Multiple previous studies in which TMAs have been used have shown that this technology produces representative results despite the small size of the samples (0.6 mm diameter).23, 25, 26, 27 The TMA approach is optimally suited for comparing frequencies of positivity between different tumor categories

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