HER2 Gene Protein Assay Is Useful to Determine HER2 Status and Evaluate HER2 Heterogeneity in HER2 Equivocal Breast Cancer.

Yanjun Hou, Hiroaki Nitta, Zaibo Li

American journal of clinical pathology 2017 Jan 01

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Approximately 15% of breast cancers show equivocal human epidermal growth factor receptor 2 (HER2) results on HER2 immunohistochemistry (IHC) and are reflexed for fluorescence in situ hybridization (FISH). However, some cases remain equivocal. In this study, we evaluated these double-equivocal cases by using a novel gene protein assay (GPA), which can simultaneously assess HER2 gene copy number and protein on a single slide using bright-field microscopy. GPA was performed on 42 HER2 IHC and FISH double-equivocal cases. GPA was negative for amplification in 28 cases, equivocal in three cases, and positive in 11 cases. The GPA results showed excellent concordance with either repeat FISH using a chromosome 17 centromere probe or FISH using an alternative probe. Furthermore, HER2 heterogeneity was identified in three of 11 GPA-positive cases. HER2 GPA performs accurately and is very useful to determine HER2 status in HER2 IHC and FISH double-equivocal breast cancer cases and identify HER2 heterogeneity. © American Society for Clinical Pathology, 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Citation

Yanjun Hou, Hiroaki Nitta, Zaibo Li. HER2 Gene Protein Assay Is Useful to Determine HER2 Status and Evaluate HER2 Heterogeneity in HER2 Equivocal Breast Cancer. American journal of clinical pathology. 2017 Jan 01;147(1):89-95