A comparative assessment of HER2 status in operable breast cancer by real-time RT-PCR and by immunohistochemistry

Background: The most commonly used methods for detecting HER2 gene amplification in breast cancer are immumohistochemistry and fluorescence in-situ hybridization. The aim of this retrospective Study was to assess HER2 expression by real-time RT-PCR. Material/Methods: Expression of HER2 was analyzed by real-time RT-PCR and immunohistochemistry in specimens of invasive ductal breast cancer tissue obtained from 131 women during radical mastectomy Results: There was a highly significant difference in mean relative gene expression between HER2-positive and HER2-negative patients as assessed by immunostaining (22.10 +/- 41.89 vs. 3.17 +/- 8.76; p<0.001). With a median follow-tip of 56 months, the cancer-specific Survival of HER2-positive patients assessed by RT-PCR was worse in all cases and in the node-positive group. In multivariate analysis, HER2 status was an independent prognostic factor in all patients. Conclusions: Real-time RT-PCR is a valuable method for determining HER2 status, but the selection of the Cutoff point of the relative gene expression differentiating between HER2-negative and -positive tumors is essential.