Evaluation of quality assurance strategies for immunohistochemistry testing in breast cancer: A literature review

Abstract

Relevance: External quality assessment (EQA) programs should be used alongside the technique to achieve accurate and reliable results when performing Immunohistochemistry (IHC) tests and diagnostics. Ensuring the accuracy of tumor biomarker tests is critically important in precision medicine since individualized treatment plans are now common in oncology.
The study aimed to systematically review evidence related to EQA in reducing inter-laboratory discrepancies and interpretative concordance variability in human epidermal growth factor receptor 2 (HER2) IHC testing for breast cancer and to identify current challenges and future directions.
Methods: This study’s systematic literature search revealed 306 records, of which 25 full-text articles were included in the final analysis. The review followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020).
Results: Recent studies suggest that EQA programs greatly improve the agreement and accuracy of HER2 IHC testing done in several laboratories. Global standards ensure standardized, reliable, and consistent HER2 testing procedures throughout the process. Moreover, new approaches like digital pathology, algorithms, and  messenger RNA (mRNA)-based tests hold great potential for improving the consistency of results and reducing judgment errors in manual reviews.
Conclusion: Implementing EQA programs has reduced variation in results from HER2 IHC across different laboratories. With the introduction of the HER2-low classification, testing methods are moving from subjective approaches to using various forms of data to improve the test’s importance to doctors. Participation in EQA enhances the efficiency of testing HER2 receptors, with the same results in several places worldwide. Having a team of experts improves the diagnosis and repeatability of breast cancer.