Clinicopathological analysis of GATA3-positive breast cancers with special reference to response to neoadjuvant chemotherapy

BackgroundThe aim of this study was to investigate the clinicopathological characteristics of GATA binding protein 3 (GATA3)-positive breast cancers as well as the association of GATA3 expression with response to chemotherapy.Patients and methodsTumor specimens obtained before neoadjuvant chemotherapy [paclitaxel followed by 5-fluorouracil/epirubicin/cyclophosphamide)] from breast cancer patients (n = 130) were subjected to immunohistochemical and mutational analysis of GATA3 and DNA microarray gene expression analysis for intrinsic subtyping.ResultsSeventy-four tumors (57%) were immunohistochemically positive for GATA3. GATA3-positive tumors were significantly more likely to be lobular cancer, estrogen receptor (ER)-positive, progesterone receptor (PgR)-positive, Ki67-negative, and luminal A tumors. Somatic mutations were found in only three tumors. Pathological complete response (pCR) was observed in 8 (11%) GATA3-positive tumors and in 22 (39%) GATA3-negative tumors. Multivariate analysis showed that tumor size, human epidermal growth factor receptor 2 (HER2), and GATA3 were independent predictors of pCR.ConclusionsGATA3-positive breast cancers showed luminal differentiation characterized by high ER expression and were mostly classified as luminal-type tumors following intrinsic subtyping. Interestingly, GATA3 was an independent predictor of response to chemotherapy, suggesting that GATA3 might be clinically useful as a predictor of a poor response to chemotherapy.