[278] Expression of Breast Specific Markers in Triple-Negative Breast Carcinomas

MJ Nystrom, ES Hwang, A Lal, I Mehdi, JT Rabban, YY Chen. University of California, San Francisco, San Francisco, CA

Background: Triple negative (ER-/PR-/HER2-, TN) breast carcinomas are aggressive tumors associated with a high incidence of metastases. However, due to their lack of staining with hormone receptors and HER2, confirmation that metastatic disease originates from a primary TN breast carcinoma can be problematic. Previous studies have evaluated expression of mammaglobin (MGB1), gross cystic disease fluid protein 15 (GCDFP-15), and androgen receptor (AR) in breast carcinomas, however there is limited data that specifically addresses expression of these breast markers in TN breast cancers. In this study, we compared the expression of MGB1, GCDFP-15 and AR in TN, ER+/HER2- (ER+), and HER2+ breast carcinomas and evaluated their efficacy as breast markers for TN tumors.
Design: The expression of MGB1, and GCDFP-15 and AR was evaluated by immunohistochemistry on tissue microarrays containing 108 TN, 44 ER+, and 27 HER2+ primary breast carcinomas. Strong cytoplasmic staining in any tumor cells was scored positive for MGB1 and GCDFP-15, while nuclear staining in more than 1% of tumor cells was considered positive for AR. A Chi-square test was used to compare the expression results between the different tumor groups.
Results: Expression of breast markers in the different tumor groups is summarized in Table 1. At least one of the three markers (MGB1, GCDFP-15, or AR) was detected in 37 (37%) of 100 TN carcinomas compared with 38 (93%) of 41 ER+ carcinomas and 27 (100%) of 27 HER2+ carcinomas.

MGB1, GCDFP-15 and AR Expression in Different Breast Tumors
MGB1 positivityGCDFP-15 positivityAR positivity
TN tumors21/98 (21%)17/107 (16%)20/101 (20%)
ER+ tumors25/42 (60%)15/39 (38%)30/40 (75%)
HER2+ tumors22/27 (81%)10/26 (38%)16/24 (67%)
p value<0.00010.004<0.0001

Conclusions: MGB1, GCDFP-15, and AR are expressed by TN breast cancers, though less frequently than in ER+ or HER2+ cancers. Never the less, their presence in carcinoma of unknown origin is strongly suggestive of a breast primary even when ER, PR and HER2 are absent.
Category: Breast

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 56, Tuesday Morning


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