Changes in HER2 status after neoadjuvant treatment of breast cancer.

Abstract

e11110 Background: Her2/neu proto-oncogene amplification and protein overexpression is observed in 20 - 40% of patients with breast cancer and play a crucial role in invasive breast cancer disease and its treatment. Number of studies have postulated the stability of Her2/neu gene expression, showing that in most patients the status of expression was not significantly changed after neoadjuvant treatment. Methods: In the present study, we investigated samples from 20 patients with invasive breast carcinoma, who underwent neoadjuvant chemotherapy and subsequent surgery. In all cases, the expression level of Her2/neu was evaluated both in pre- therapeutically obtained tumor tissue by core needle biopsy and in speciemen removed by final surgery, using immunohistochemistry (IHC). Fluorescence in situ hybridization (FISH) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) methods were used for verification of the results obtained by IHC. Results: In the present study, Her2/neu status determined by immunohistochemistry remained unchanged in 12 of 20 (60%) patients after neoadjuvant treatment. In six cases (30%) minor changes was observed due to the treatment. However, in two cases (10%) we found Her2/neu expression alteration from strongly positive in pre-treatment biopsy to negative in post-treatment surgery specimen. Conclusions: This is the first report which describes the changes in Her2/neu status on all protein, RNA and DNA levels by using immunohistochemistry (IHC), quantitative reverse transcription polymerase chain reaction (qRT-PCR) and fluorescence in situ hybridization (FISH), respectively. This work was supported by Grant IGA MZ CR NS/10575-3.