The goal of the study was to identify a gene expression signature capable of predicting a pathological complete response following neoadjuvant anthracycline-based chemotherapy of breast cancer. The samples were taken from the FEC arm (5-fluorouracil, epirubicin, cyclophosphamide) of the EORTC 10994 trial. EORTC 10994 is a phase III clinical trial comparing FEC with ET (epirubicin, docetaxel) in patients with large operable, locally advanced or inflammatory breast cancer (www.eortc.be). Frozen biopsies were taken at randomisation. RNA was extracted from 100um thickness of 14G core needle biopsies. Adjacent sections were tested by H&E to confirm >20% tumour cell content. 200 ng total RNA per chip was amplified using the Affymetrix small sample protocol (IVT then Enzo). 102 tumours were tested on Affymetrix X3P chips. Single biopsies were tested per tumour. The CEL files were quantile normalised using rma. The clinical response measure was pathological complete response (pCR, disappearance of the tumour after chemotherapy with at most scattered invasive cells detected by histology).
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