Characterization of HER1 (c-erbB1) status in locally advanced breast cancer using fluorescence in situ hybridization and immunohistochemistry

Epidermal growth factor receptor ( EGFR) is a 170-kDa transmembrane glycoprotein encoded by the HER1 protooncogene, located at 7p12. This receptor is related to the pathogenesis of breast cancer. The aim of this study was to analyze the status of HER1 using fluorescence in situ hybridization ( FISH) and immunohistochemistry in a series of 48 patients with locally advanced breast cancer (LABC). Before neoadjuvant chemotherapy, core biopsies were taken from patients with LABC and were processed into paraffin blocks. Biopsies were then studied using FISH with a HER1 probe (Vysis, Downers Grove, Ill., USA). They were also analyzed immunohistochemically using two different EGFR antibodies from DakoCytomation ( Denmark, A/S) and from Zymed ( San Francisco, Calif., USA). HER1 amplifications were not found, although 31% of the cases presented aneusomy of chromosome 7. Only 2 cases presented EGFR expression. LABC presented a low level of EGFR expression. HER1 amplification was not present in LABC, although the polysomy of chromosome 7 was a common finding. Copyright (C) 2005 S. Karger AG, Basel.