Influence of neoadjuvant therapy with epirubicin and docetaxel on the expression of HER2/neu in patients with breast cancer

Background. In primary breast cancer, the expression levels of biological markers relevant to the progression of the disease may be altered by administration of anticancer drugs. Since neoadjuvant chemotherapy with epirubicin and docetaxel is increasingly used in advanced breast cancer, our purpose was to assess the influence of this neoadjuvant chemotherapy on the expression of the growth factor receptor HER2/neu. Patients and methods. We investigated changes of HER2/neu status by immunohistochemistry (IHC) and applied additional fluorescence in situ hybridization (FISH) in patients with potential modulation of HER2/neu status after administration of neoadjuvant chemotherapy with docetaxel and epirubicin in 97 breast cancer patients. The influence of neoadjuvant chemotherapy on HER2/neu expression was calculated by correlation of HER2/neu status before and after chemotherapy. Results. The accuracy of HER2/neu assessment before and after neoadjuvant chemotherapy by IHC combined with FISH analysis in selected cases was 100%. The evaluation of HER2/neu status in these patients by IHC alone yielded accuracy of 93%. Neoadjuvant chemotherapy with epirubicin and docetaxel caused no significant modulation of HER2/neu status (p=0.66). Discussion. The administration of epirubicin and docetaxel in the neoadjuvant setting is not associated with significant changes of HER2/neu status in primary breast cancer. As a consequence, drug resistance or sensitivity is not induced by modulation of HER2/neu expression. Moreover, the time of assessment of the HER2/neu status is not a critical factor under neoadjuvant therapy with epirubicin and docetaxel.