HER-2/neu: a differentiation marker in adenocarcinoma of the esophagus.

Adenocarcinoma of the esophagus is an aggressive malignancy which is increasing in frequency. The HER-2/neu oncogene product is a putative differentiation marker which exhibits decreased expression in colon carcinoma, while there is overexpression in breast and ovarian cancers. We analyzed the relationship of cell differentiation to HER-2/neu expression in esophageal adenocarcinoma using immunohistochemistry on formalin-fixed, paraffin-embedded material from 14 patients whose tissue contained normal, dysplastic, and malignant features. HER-2/neu expression was detected in 1 of 14 biopsy specimens and 2 of 9 resection specimens. The oncoprotein staining was greatest in normal tissue, less in dysplastic tissue, and not detected in malignant tissue. Our findings, similar to what is seen in the colon, suggest that the HER-2/neu oncogene product is a differentiation marker which is lost in esophageal adenocarcinoma.