Journal of Medical Diagnostic Methods
Open Access

Evaluation of Clinical Laboratory Methods for HER2 Testing

Liang Hunig^{* *}Correspondence: Liang Hunig, Department of Medicine, University of Cambridge, Cambridge, England, Email:

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Description

One biomarker that is essential to the treatment of breast cancer is Human Epidermal Growth Factor Receptor 2 (HER2). A poor prognosis and aggressive tumor behavior are linked to HER2 overexpression or amplification; nevertheless, HER2 can also be targeted therapeutically with some anti-HER2 treatments. To maximize patient outcomes and guide treatment options, an accurate evaluation of HER2 status is necessary. For HER2 testing, several laboratory techniques are used; each has advantages, disadvantages, and technical issues. This paper addresses the assessment of clinical laboratory procedures for HER2 testing, highlighting the significance of quality control, interpretation guidelines, and assay standardization.

Immunohistochemistry (IHC)

When evaluating HER2 protein expression in tumor tissue samples, Immunohistochemistry (IHC) is a commonly utilized technique. Formalin-fixed, paraffin-embedded tissue slices are exposed to HER2-specific antibodies, and the resulting antigen is then detected using fluorescent or chromogenic substrates. ASCO/CAP recommendations or the Hercep Test grading system are commonly used to interpret IHC data, taking into account the distribution and intensity of HER2 staining.

Assessing the sensitivity, specificity, repeatability, and concordance of IHC tests with other HER2 testing techniques, such Fluorescence In Situ Hybridization (FISH), is part of the evaluation process. To identify the best antibody clone, detection method, and scoring algorithm for precise HER2 evaluation, validation tests are carried out. To guarantee the uniformity and dependability of IHC findings across various laboratories, quality assurance procedures such as proficiency testing and external quality evaluation programs are crucial.

Fluorescence In Situ Hybridization (FISH)

A molecular method called Fluorescence In Situ Hybridization (FISH) is used to find HER2 gene amplification in tumor cells. Fluorescence microscopy is used to visualize the hybridization of fluorescently labelled DNA probes that target the HER2 gene locus on chromosome 17. The ratio of HER2 gene signals to chromosome 17 signals is used to interpret FISH data; a HER2/ CEP17 ratio of > 2.0 is thought to be suggestive of HER2 gene amplification.

Analytical sensitivity, specificity, repeatability, and concordance with other HER2 testing techniques, especially IHC, are all evaluated in relation to FISH tests. To achieve accurate HER2 gene copy number assessment, validation studies are carried out to optimize the hybridization conditions, scoring criteria, and probe selection. Inter laboratory proficiency testing and standardizing interpretation guidelines are two important quality assurance techniques that are necessary to guarantee the dependability and uniformity of FISH findings across various laboratories.

Next-Generation Sequencing (NGS)

For HER2 testing in breast cancer, Next-Generation Sequencing (NGS) is a high-throughput genomic profiling method that may be applied. With a single experiment, NGS enables the simultaneous identification of many genetic changes, such as HER2 gene amplification, mutations, and rearrangements. More molecular characterization of tumor samples is provided by NGS, which may have advantages over more conventional techniques like IHC and FISH.

Analytical performance aspects of NGS-based HER2 testing are evaluated by comparing it to conventional reference techniques in terms of sensitivity, specificity, accuracy, and repeatability. To accurately determine the HER2 status, validation studies are carried out to optimize bioinformatics pipelines, variant interpretation algorithms, and sequencing procedures. The reliability and uniformity of NGS findings across several facilities are dependent on quality assurance procedures including variant classification criteria standardization and proficiency testing.

Challenges and considerations

Standardization: For the findings of HER2 testing to be consistent and comparable amongst laboratories, standardization of assay techniques, interpretation guidelines, and reporting criteria is necessary.

Quality Assurance: The accuracy and dependability of HER2 testing assays must be monitored and maintained through the use of strong quality assurance techniques, such as proficiency testing, external quality evaluation programs, and internal quality control processes.

Interpretation Guidelines: In order to reduce inter observer variability and guarantee consistent HER2 status categorization, it is imperative to establish unambiguous and uniform standards for interpreting HER2 test findings.

Technical Considerations: HER2 testing assay performance and reliability can only be maximized by taking into account technical aspects, such as tissue processing procedures, antigen retrieval techniques, and platform-specific parameters.

Conclusion

Making informed decisions about therapy and improving prognoses for patients with breast cancer requires accurate HER2 status determination. The assessment of several assays, including as immunohistochemistry, fluorescence in situ hybridization, and next-generation sequencing, as well as validation studies and quality assurance metrics, are part of the evaluation of clinical laboratory procedures for HER2 testing. To guarantee the accuracy and practical use of HER2 testing assays in everyday practice, it is imperative to tackle crucial elements such as standardization, quality control, recommendations for interpretation, and technological issues. Clinical professionals may more successfully identify patients who can benefit from HER2-targeted medicines by optimizing HER2 testing techniques, which will enhance patient care and treatment results for breast cancer patients.