Cytoplasmic expression of c-erb-B2 in endometrial carcinomas

The aim of this study was to investigate the expression of c-erb-B2 in endometrial cancer with attention to both membranous and cytoplasmic staining, and to elucidate the significance of cytoplasmic signaling.

c-erb-B2 reactivity was assessed by immunohistochemistry in 110 patients using a polyclonal antibody, and evaluated semiquantitatively according to the percentage of cells demonstrating membranous or diffuse cytoplasmic staining. Correlation was made with tumor stage, grade, myometrial invasion, histologic type, and disease outcome.

c-erb-B2 overexpression, indicated by membranous and cytoplasmic staining of at least 10% of the tumor cells, was found in 47 (42.7%) cases. Cytoplasmic expression of c-erb-B2 was observed more frequently than membranous (69.1 vs. 5.5%). Synchronous cytoplasmic and membranous signaling was noticed in 7.9% of cases. Interestingly, patients with cytoplasmic c-erb-B2-positive tumors had a significantly shorter survival (p = 0.047).

These results indicate that c-erb-B2 is a specific marker of endometrial cancer. It is also an independent prognostic indicator of poor outcome. Cytoplasmic staining is as important as membranous staining, and is also a specific finding.