[140] GATA3 Expression in Different Subtypes of Invasive Breast Carcinoma and Comparison with GCDFP15 and Mammaglobin

Georgios Deftereos, Uma Krishnamurti, Jan F Silverman. Allegheny General Hospital, Pittsburgh, PA

Background: GATA3 (GATA binding protein 3) is a transcription factor that has a role in cell proliferation and differentiation in many tissues, including the breast and is fairly specific for breast and urological cancers. It has been suggested that low GATA3 expression in breast carcinomas (BC) correlates with a worst prognosis. However, there is little data available on GATA3 expression in the various histologic subtypes of invasive BC.
Design: 59 cases of invasive BC, including 14 ductal, 12 lobular, 12 micropapillary, 10 pleomorphic lobular, 4 ductal with apocrine features, 4 mucinous and 3 medullary carcinomas were selected and immunostained for GATA3, GCDFP15 and mammaglobin. For GATA3, stain intensity was graded as 1+, 2+ and 3+ and an H-score was calculated by multiplying the stain intensity with the percentage of tumor cells staining. GATA3 staining was examined in the various histologic subtypes and compared with GCDFP15 and mammaglobin reactivity. Correlations with nuclear grade, ER, PR and HER2 status were also investigated.
Results: Of the 59 cases, GATA3 was positive in all 59 (100%) BC, while GCDFP15 and mammaglobin were positive only in 23 (38.98%) and 31 (52.54%) cases, respectively. GATA3 was positive in all 26 (100%) cases with grade 3 nuclei, while GCDFP15 and mammaglobin were positive only in 5 (19.23%) and 11 (42.31%) cases, respectively. ER-positive carcinomas had significantly higher GATA3 expression when compared with ER-negative carcinomas (mean H-score of 279 vs. 161; p<0.0001). 100% (n=8) cases of triple-negative carcinomas also stained with GATA3, significantly more than GCDFP15 (37.5%, p<0.0001) or mammaglobin (12.5%; p<0.0001). Staining for GATA3 was also qualitatively superior compared to GCDFP15 and mammaglobin, showing less background staining, particularly in cases of mucinous BC, where the mucin showed no staining, in contrast to the other two immunomarkers.
Conclusions: GATA3 shows a higher sensitivity, compared to GCDFP15 and mammaglobin in BC with uniform expression in all histologic subtypes and with lower background staining. There is correlation between ER-positivity and higher GATA3 expression, regardless of the histologic subtype. GATA3 is significantly more sensitive in both high nuclear grade and triple-negative BC than the other IHC breast markers. In addition, we believe that GATA3 is a useful antibody in the work-up of metastatic cancer where BC is considered in the differential diagnosis.
Category: Breast

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 18, Monday Morning


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