[244] Expression of Estrogen Receptor β Isoforms in Male and Female Breast Carcinoma

TS Kraus, D Lawson, C Cohen. Emory University, Atlanta, GA

Background: Recent studies have suggested that differential expression of estrogen receptor (ER)β isoforms may have prognostic and therapeutic implications in breast carcinoma. ERβ expression has also been shown in "triple-negative" (ER-, progesterone receptor {PR}-, HER2-) breast carcinoma. Previous studies have focused predominantly on female breast carcinoma (FBC), and data comparing expression of ERβ isoforms in FBC and male breast carcinoma (MBC) are limited. In this study, we compared expression of ERα, ERβ2, ERβ5, PR, and HER2 in FBC and MBC.
Design: Immunohistochemical stains for ERα, ERβ2, ERβ5, PR, and HER2 were performed on tissue microarrays representing 32 MBC (four 1.0 mm cores per case) and 82 FBC (two 1.0 mm cores per case). Nuclear staining for hormone receptors was scored using the Allred system. Membranous HER2 staining was scored according to CAP guidelines.

ERα23/27 (85%)49/73 (67%)0.085
ERβ22/25 (8%)3/67 (4%)0.610
ERβ518/23 (78%)22/67 (33%)0.0002
PR14/27 (52%)40/76 (53%)1
HER26/26 (23%)14/63 (22%)1

All ERβ2-positive cases were positive for ERα. Although the majority of ERβ5-positive cases were ERα-positive, ERβ5 was expressed in two of two (100%) triple-negative MBC and in six of 12 (50%) triple-negative FBC.
Conclusions: In our series, ERβ5 expression was significantly more common in MBC than in FBC. This occurred in both ERα-positive and triple-negative carcinomas, although the number of the latter was small. Expression of all other studied markers was similar in both groups. As more is learned about the significance of ERβ subtypes in the pathogenesis of breast carcinoma, the observed differences in ERβ5 expression in MBC and FBC may provide insight about biological differences in MBC and FBC, and provide a potential therapeutic target.
Category: Breast

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 23, Monday Morning


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