Basal-like molecular subtype and HER4 up-regulation and response to neoadjuvant chemotherapy in breast cancer.

Alteration of gene expression profiles during chemotherapy may predict response to neoadjuvant chemotherapy (NAC) in breast cancer patients. In a prospective cohort study of 32 women with primary invasive breast cancer, we obtained tumor specimens before and after 4 cycles of NAC with epirubicine 90 mg/m2 and cyclophosphamide 600 mg/m2, followed by 4 cycles of docetaxel 100 mg/m2. Total-RNA was extracted from tumor specimens and the whole transcriptome was analyzed with Agilent's 44K single color microarray.