The main clinical significance of HER-2/neu gene amplification is derived from its use as (a) a prognostic indicator, (b) a predictive factor for the sensitivity to chemotherapy, and (c) the identification of cases that are eligible for a specific therapy targeting the HER-2/neu protein. Overexpression of HER-2/neu has been shown to be associated with a poor prognosis for patients with node-positive breast cancer and also possibly for patients with node-negative breast cancer. The purpose of this work was to analyze the HER-2/neu gene amplification and correlate it with other clinico-pathologic parameters.

The study population consisted of 194 patients with breast cancer who had been treated with curative surgery at the Kangdong Sacred Hospital, Seoul, Korea from 1995 to 2000. Paraffin-embedded tissue samples from the primary tumors were obtained from the hospital archives and the tissue microarray was then constructed. We analyzed the amplification of HER-2/neu gene by the two-color FISH (Fluorescence in situ hybridization) method, and we correlated the results with other clinico-pathologic parameters such as tumor size, stage, histologic grade, lymph node status and hormonal receptor status.

For 44 cases (22.7%) of a total 194 cases, the HER-2/neu gene was amplified. HER-2/neu gene amplification was positively correlated with TNM stage and lymph node status, and it was inversely correlated with estrogen receptor positivity.

For breast cancer, the analysis of the HER-2/neu gene by FISH based on a tissue microarray may be useful.