Molecular protocol for HER2/neu analysis in breast carcinoma

The HER2/neu proto-oncogene is frequently over-expressed in breast cancer and serves as a biological target for trastuzumab therapy. However, there is no consensus regarding the technical aspects to be used to define HER2/neu status in clinical practice. The present study was conducted to address th...

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Published in:	Clinical & translational oncology 2005-12, Vol.7 (11), p.504
Main Authors:	Artufel, Montse Verdú, Valero, Anna Colomer, Lladó, Ruth Román, Sagalés, Nadina Erill, Llorca, Miquel Calvo, Carazo, Abelardo Moreno, Cardó, Carlos Cordón, Torrus, Xavier Puig
Format:	Article
Language:	spa
Subjects:	Adenocarcinoma, Mucinous - chemistry Adenocarcinoma, Mucinous - genetics Adult Aged Aged, 80 and over Algorithms Antibodies, Monoclonal - immunology Breast Neoplasms - chemistry Breast Neoplasms - genetics Breast Neoplasms, Male - chemistry Breast Neoplasms, Male - genetics Carcinoma, Ductal, Breast - chemistry Carcinoma, Ductal, Breast - genetics Carcinoma, Lobular - chemistry Carcinoma, Lobular - genetics False Positive Reactions Female Gene Amplification Genes, erbB-2 Humans Immunoenzyme Techniques In Situ Hybridization, Fluorescence Male Middle Aged Neoplasm Proteins - analysis Neoplasm Proteins - genetics Neoplasm Proteins - immunology Prospective Studies Receptor, ErbB-2 - analysis Receptor, ErbB-2 - immunology Sensitivity and Specificity
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Summary:	The HER2/neu proto-oncogene is frequently over-expressed in breast cancer and serves as a biological target for trastuzumab therapy. However, there is no consensus regarding the technical aspects to be used to define HER2/neu status in clinical practice. The present study was conducted to address this critical issue by prospectively analysing a large cohort of breast cancer patients (n = 222) and using a variety of methods. To define HER2/neu expression, detection of its encoded protein (p185) was performed by comparative immunohistochemical (IHC) analysis using two mouse monoclonal antibodies (mAb CB11 and mAb TAB250). To assess HER2/neu gene amplification, fluorescent in situ hybridisation (FISH) assays with gene-specific probes were conducted. All procedures were applied to de-paraffinised tissue sections of breast tumour samples. Results showed that mAb CB11 had increased sensitivity and specificity (62.5% and 93.4%, respectively) compared to mAb TAB250 (40% and 76.4%, respectively) in defining HER2/neu amplification. We conclude that HER2/neu measurement by IHC using mAb CB11 is an appropriate strategy which provides a high negative predictive value (95.5%) for HER2/neu amplification in cases with low or undetectable p185 expression. Conversely, mAb CB11 has a high positive predictive value (96.2%) for HER2/neu amplification in cases with p185 overexpression. However, cases with moderate p185 expression need to be considered as inconclusive. In such cases, it is necessary to use FISH measurement to evaluate HER2/neu amplification. It is also advisable to conduct FISH if there is discordance between p185 expression and the histopathology classification of the lesion, or molecular profile of the tumour. Finally, even though the false positive rate of IHC assay is
ISSN:	1699-048X 1699-3055