Necessity of In Situ Hybridization Test of Human Epidermal Growth Factor Receptor 2 (HER2) Status in Breast Cancer Patients with Equivocal HER2 Immunohistochemistry Results

Context Human epidermal growth factor receptor 2 (HER2/neu) amplification is used as a predictive marker for trastuzumab treatment in breast cancer. Both immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) testing algorithms have been based on the 2007 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines. In late 2013, the guidelines were updated with new scoring criteria. Objective —To assess the impact of the revised ASCO/CAP recommendations on both IHC and FISH results by using the dual-color HER2/neu and centromeric FISH probes. Design Retrospective analysis of 590 invasive carcinomas with concurrent IHC and dual-color HER2/neu and centromeric 17 (CEP17) FISH results, based on 2007 ASCO/CAP guidelines, was conducted from July 2011 to June 2013. With the revised guidelines, patients were recategorized and concordance rates between the 2 assays were recalculated. Results —Overall concordance rates for FISH and IHC decreased from 94.9% to 93.8% with reclassification. Negative FISH cases decreased from 79.1% to 69.3%. However, equivocal FISH cases were significantly increased from 0.7% to 9.5%, leading to more retesting. Both positive IHC and FISH cases were also noted to be increased, leading to more patients being eligible for trastuzumab treatment, especially those patients with concurrent HER2/neu and CEP17 polysomy. Approximately 1% of patients with initial FISH negative results were reclassified as having positive results when both the ratios and average copy number of HER2/neu were considered under the revised guidelines. Conclusions The revised 2013 ASCO/CAP guidelines can potentially lead to more patients being eligible for trastuzumab therapy but additional retesting is to be expected owing to an increased number of equivocal FISH cases.

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Human epidermal growth factor receptor 2 testing in breast cancer

Medicinski pregled ◽

10.2298/mpns1002069i ◽

2010 ◽

Vol 63 (1-2) ◽

pp. 69-74 ◽

Cited By ~ 1

Author(s):

Tatjana Ivkovic-Kapicl ◽

Slavica Knezevic-Usaj

Keyword(s):

Breast Cancer ◽

Epidermal Growth Factor Receptor ◽

In Situ Hybridization ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Gene Amplification ◽

Growth Factor Receptor ◽

Epidermal Growth

Introduction. Testing for human epidermal growth factor receptor-2 in breast cancer at the time of primary diagnosis is now the standard of care. Positivity for epidermal growth factor receptor-2 in breast cancer is a prognostic factor regarding tumor aggressiveness and a predictive factor for response to Herceptin. Accurate assessment is essential to ensure that all patients who may benefit from Herceptin are correctly identified. Assay method. The principal testing methods used for determination of epider?mal growth factor receptor-2 status are immunohistochemistry for protein over expression and in situ hybridization using either fluorescence or a chromogen. Immunohistochemical testing method allows identification of epidermal growth factor receptor-2 positive patients (3+) who may benefit from Herceptin therapy, whereas negative patients (0/1+) can be excluded. A proportion of specimens defined as equivocal by immunohistochemistry (2+) must be retested by in situ hybridization to determine their status. Chromogen in situ hybridization is a method for determination of gene amplification using a peroxidase-based chromogenic reaction, which can be viewed using a conventional bright field microscope and it determines the actual degree of gene amplification. Various factors can affect the results achieved with these assays, including the assay antibody/probe, the methodology and the experience of personnel. Many countries implemented national testing guidelines in an attempt to standardize testing procedures and make results more accurate. Conclusion. The key point underlined by this review is that whatever method is used to test HER2 status, the technology must be validated first, and there must be regular internal and external quality assurance procedures.

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Utility of Alternate, Noncentromeric Chromosome 17 Reference Probe for Human Epidermal Growth Factor Receptor Fluorescence In Situ Hybridization Testing in Breast Cancer Cases

Archives of Pathology & Laboratory Medicine ◽

10.5858/arpa.2017-0252-oa ◽

2018 ◽

Vol 142 (5) ◽

pp. 626-633 ◽

Cited By ~ 2

Author(s):

Trupti Pai ◽

Tanuja Shet ◽

Asawari Patil ◽

Omshree Shetty ◽

Angad Singh ◽

...

Keyword(s):

Epidermal Growth Factor Receptor ◽

In Situ Hybridization ◽

Growth Factor ◽

Growth Factor Receptor ◽

Chromosome 17 ◽

Her2 Status ◽

Breast Cancers ◽

Reference Probe ◽

Epidermal Growth

Context PathVysion—a US Food and Drug Administration–approved dual-probe human epidermal growth factor receptor (HER2) fluorescence in situ hybridization (FISH) assay—provides the HER2:CEP17 ratio, a centromeric enumeration probe ratio for determining HER2 status in breast cancers. However, pericentromeric amplifications might then skew the HER2:CEP17 ratio, underestimating the HER2 status, which calls into question the use of CEP17 as the reference probe. Objective To analyze the utility of a noncentromeric chromosome 17 reference locus (D17S122) to assess HER2 gene status in cases showing “nonclassical” FISH patterns with the CEP17 probe. Design The HER2 status of breast cancers accessioned in the years 2015–2017, displaying “nonclassical” or “equivocal” results by the PathVysion (Abbott Molecular Inc, Des Plaines, Illinois) HER2 DNA Probe Kit were reflex tested using an alternate FISH probe (ZytoLight SPEC/D17S122, ZytoVision, Bremerhaven, Germany) and interpreted with American Society of Clinical Oncology/College of American Pathologists 2013 guidelines. Results Of 37 cases, 17 were FISH equivocal. With the alternate D17S122 probe, 13 (76.4%) were reclassified as amplified, 3 (17.6%) as nonamplified, and a single case retained an equivocal result. Of the 17 cases with a chromosome 17 polysomy pattern, disomy, polysomy, and monosomy patterns were seen with 14 cases, 2 cases, and 1 case, respectively. Within the 17 cases with polysomy pattern, 3 (17.6%) demonstrated an unusual colocalization pattern of HER2 and CEP17, which was not observed with the alternate probe. Conclusions The denominator-stable alternate probe is a useful adjunct in the diagnostic armamentarium to analyze HER2 status in cases with FISH equivocal and complex patterns.

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Quantitative Impact of the 2018 American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) Practice Guideline Update on Human Epidermal Growth Factor Receptor 2 (HER2) Testing in Breast Cancer: A Systematic Analysis

Archives of Pathology & Laboratory Medicine ◽

10.5858/arpa.2020-0378-oa ◽

2020 ◽

Author(s):

Christina H. Wei ◽

Lino Garcia ◽

Joyce Murata-Collins ◽

Daniel Schmolze ◽

Sophia Apple

Keyword(s):

Epidermal Growth Factor Receptor ◽

In Situ Hybridization ◽

Growth Factor ◽

Fluorescence In Situ Hybridization ◽

Growth Factor Receptor ◽

Her2 Status ◽

Epidermal Growth ◽

American Society ◽

Quantitative Impact

Context.— The global impact of the new 2018 American Society of Clinical Oncology/College of American Pathologists human epidermal growth factor receptor 2 (HER2) practice guideline update on the overall HER2 status designation, compared with the prior 2013 iteration, is unknown. Objectives.— To report the quantitative impact of the new guideline on HER2 status distribution. Design.— The analysis comprised a retrospective cohort of patients from the author's institution, combined with other peer-reviewed publications that assessed the impact of the 2018 guideline in relation to the 2013 guideline. Results.— Our study revealed that the new guideline led to an average 9% reclassification rate for the overall HER2 status, with a net gain in overall HER2 negative designation. This is largely due to reclassification of the equivocal (Group 4) groups. Unexpectedly, infrequent but consistent discordance between Group 1/5 and fluorescence in situ hybridization results are observed across studies (1.8%; 73 of 3965 cases where fluorescence in situ hybridization and immunohistochemistry are both reported). Conclusions.— Early clinical recognition of these resultant changes, including emerging issues of tumor heterogeneity, and potential discordance between immunohistochemistry to fluorescence in situ hybridization, is important for accurate clinical assessment of individual HER2 test results.

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