OCT 13, 2020 4:30 PM SGT

How to Improve HER2 testing Accuracy: Incorporating the 2018 ASCO/CAP Focused Update

C.E. Credits: P.A.C.E. CE Florida CE
  • Medical Director Vitro Molecular Laboratorios Miami, FL

      A graduate from Damascus University School of Medicine, Dr. Hadi Yaziji is an American Board-certified pathologist who did his pathology training at the University of Louisville Hospitals, then went on to do two sub-speciality fellowships in Surgical Pathology and Breast Pathology and Immunohistochemistry at the University of Washington, followed by a third fellowship in Cytopathology at MD Anderson Cancer Center. For over 20 years of his medical career, Dr. Yaziji has given numerous talks at local, national and international pathology conventions, presented his research that focuses on targeted therapy biomarker testing at international pathology meetings, and published his work at many peer-reviewed indexed medical journals. Dr. Yaziji's area of expertise is breast pathology and breast cancer biomarkers, especially HER2 protein and gene testing. Dr. Yaziji is the founder of Vitro Molecular Laboratories, an international specialty anatomic pathology laboratory, and is also the founder of Pathology Learning Centers, a medical education organization that offers the most comprehensive course on specialized testing in anatomic pathology. Board certified in Anatomic Pathology, Clinical Pathology and Cytopathology, Dr. Yaziji also received several prestigious achievement awards, including Alpha Omega Alpha Honor Medical Society and the Southern Medical Association (Pathology Section) achievement award. He also co-authored over 55 publications in peer-reviewed journals.


    The mechanism of HER2 protein expression in tumors is primarily gene amplification, primarily enabled via the process of dimerization of HER2 receptors. Anytime there is a discrepancy, which is exceedingly rare, between protein and gene status, we rely more on the protein status rather than gene status for treatment purposes because the drug doesn’t target the gene. There are common misconceptions that low grade tumors, lobular, mucinous “tubular” tumors and tumors with incomplete membranous signal are always HER2 negative. Additionally, there is the misconception that most HER2-positive tumors are high grade. ASCO/CAP 2018 update moved closer to performing Immunohistochemistry (IHC) & FISH (Fluorescence) on all tumors and recommends the use of dual-probe instead of single-probe IHC assays. 2018 Guidelines swing the pendulum in the “negative results” direction. As this will not solve the dilemma of the “gray zone” group, we propose a 3-tier scoring of HER2 status as either positive, negative or low as this will not solve the dilemma of the “gray zone” group. Our QA program includes tumor analysis, nuclear score, tumor histological grade, IHC score and FISH score. Correlation with IHC and tumor histopathology and performing metrics is mandatory in order to improve HER2 testing accuracy.

    Learning Objectives:

    • Understand the impact of HER2 between the protein and gene status
    • Understand the role of IHC & FISH in breast cancer diagnosis

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