EGFR gene and protein expression in breast cancers

Aims: To measure the EGFR gene amplification and protein expression, and to compare the EGFR expression with HER2 expression similarly measured. Methods: EGFR gene amplification was assayed by fluorescence in situ hybridization and its protein expression was evaluated by immunohistochemistry on tissue microarray of 165 consecutive invasive breast cancers. Results: EGFR protein overexpression was observed in 20.6% of the 165 studied cases, but gene amplification was observed in 7.9% only. EGFR protein was expressed in 33.3% of HER2-amplified tumors, and in only 16.3% of HER2 non-amplified tumors. EGFR expression significantly increased in HER2 gene-amplified and protein-expressing tumors as well. On survival analysis, EGFR expression was a significant prognostic factor for the disease-free and overall survival of the patients. Conclusions: EGFR protein expression was independent of EGFR gene amplification status, whereas it was intimately associated with HER2 amplification and overexpression in breast cancer. (C) 2007 Published by Elsevier Ltd.