Prognostic markers in breast cancer: the reliability of HER2/neu status in core needle biopsy of 325 patients with primary breast cancer.

ABSTRACT

INTRODUCTION: The assessment of HER2/neu overexpression in tissue provides information about one of the most relevant prognostic and predictive markers in breast cancer overexpression of HER2/neu is associated with worse prognosis in primary breast cancer. Since core needle biopsy is increasingly used for the diagnosis of breast cancer, the purpose of this study was to assess the reliability of HER2/neu evaluation using this technique in patients with primary breast cancer. PATIENTS AND METHODS: We investigated the accuracy of immunohistochemical assessment of HER2/neu in core needle biopsies compared with surgically obtained specimens in 325 patients with primary breast cancer. In patients strongly positive for HER2/neu, additional fluorescence in situ hybridization (FISH) analysis of needle biopsies was performed. RESULTS: Using immunohistochemistry alone, accuracy of HER2/neu assessment in core biopsies in relation to surgically removed specimens was 92% and increased to 96% with additional FISH analysis (weighted Kappa coefficient 0.86). DISCUSSION: As proven with this large series of patients, the assessment of HER2/neu status by core needle biopsy in breast cancer is accurate. Notwithstanding, in order to minimize the number of false-positive results, strongly positive core needle biopsies identified using immunohistochemistry should be confirmed by FISH analysis.