Determination of HER2 gene amplification by fluorescence in situ hybridization and concordance with the clinical trials immunohistochemical assay in women with metastatic breast cancer evaluated for treatment with trastuzumab.

Purpose: To evaluate the concordance between HER2 gene amplification, determined by fluorescence in situ hybridization (FISH), and HER2 protein overexpression assessed by an immunohistochemical (IHC) assay. The IHC protocol used was a research assay, known as the Clinical Trial Assay (CTA), developed to select women with metastatic breast cancer (MBC) for three pivotal clinical trials of trastuzumab therapy.

Methods: A direct-labeled, dual-probe FISH assay was used to determine HER2 amplification in 623 fixed breast cancer tissue specimens.

Evaluation of clinical outcomes according to HER2 detection by fluorescence in situ hybridization in women with metastatic breast cancer treated with trastuzumab.

Background: We evaluated the influence of HER2 gene amplification, as determined by fluorescence in situ hybridization (FISH), on clinical outcomes (objective response rates, time to disease progression, and overall survival time) in women with metastatic breast cancer treated with trastuzumab in 3 clinical trials. Breast cancer tissue specimens were evaluated using a direct labeled, dual-probe FISH assay.

Materials And Methods: Specimens with a HER2:CEP17 ratio of > or = 2:0 were considered positive for gene amplification.