To identify FISH-Positive HER-2 Testing Results Based on Current American Society of Clinical Oncology / College of American Pathologists (ASCO/CAP) Guidelines

Rodrigo Arrangoiz MS, MD, FACS, FSSO

👉HER-2 expression in breast cancer is primarily assessed semiquantitatively by IHC.

👉The 2013 ASCO guidelines outline an IHC scoring method based on four classes:

– 0, 1+, 2+, and 3+.

👉A score of 0 is negative, indicating no observed staining in invasive tumor cells.

👉A score of 1+ is negative and indicates weak, incomplete membrane staining in any proportion of invasive tumor cells or weak, complete membrane staining in less than 10% of invasive tumor cells.

👉A score of 2+ is equivocal, indicating circumferential membrane staining that is incomplete and/or weak/moderate and in more than 10% of invasive tumor cells or complete and circumferential membrane staining that is intense and in 10% or less of invasive tumor cells.

👉All 2+ equivocal cases undergo subsequent testing by FISH.

👉A score of 3+ is positive and indicates circumferential membrane staining that is complete and intense in a homogeneous and contiguous population, present in more than 10% of invasive tumor cells, and readily appreciated using a low-power objective. 

👉FISH is a sensitive and accurate method of scoring invasive breast tumor tissue for HER-2 expression.

👉Initial gene amplification studies by FISH assessment used chromosome 17 centromere (CEP17) or another gene on the same chromosome as an internal control, with a ratio of 2.0 or more considered evidence of HER-2 amplification.

👉These criteria were used as the cutoff for enrollment in trials evaluating HER-2 targeted therapies.

👉In 2007, the ASCO/CAP guidelines were changed to define HER-2 amplified as a ratio of 2.2 or more.

👉More recent guidelines have changed the ratio cutoff back to a ratio of 2.0 or more with the inclusion of criteria to account for HER-2 copy number per tumor cell.

👉Based on the recent guidelines, HER-2 is amplified in cases where the HER-2/CEP17 ratio is 2.0 or more with an average HER-2 copy number of less than 4.0 signals/cell or the HER-2/CEP17 ratio is less than 2.0 with an average HER-2 copy number of 6.0 or more signals/cell using a dual probe or a HER-2 copy number of 6.0 or more copies/cell using a single probe.

👉FISH testing is negative for HER-2 amplification with a HER-2/CEP17 ratio of less than 2.0 with an average HER-2 copy number of less than 4.0 signals/cell or an average HER-2 copy number of less than 4.0 signals/cell using a single probe.

👉Rodrigo Arrangoiz MS, MD, FACS cirujano oncology y cirujano de mama miembro de Sociedad Quirúrgica S.C en el America British Cowdray Medical Center en la ciudad de Mexico:

  • Es experto en el manejo del cáncer de mama.

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Published by Rodrigo Arrangoiz MS, MD, FACS, FSSO

My name is Rodrigo Arrangoiz I am a breast surgeon/ thyroid surgeon / parathyroid surgeon / head and neck surgeon / surgical oncologist that works at Center for Advanced Surgical Oncology in Miami, Florida. I was trained as a surgeon at Michigan State University from (2005 to 2010) where I was a chief resident in 2010. My surgical oncology and head and neck training was performed at the Fox Chase Cancer Center in Philadelphia from 2010 to 2012. At the same time I underwent a masters in science (Clinical research for health professionals) at the University of Drexel. Through the International Federation of Head and Neck Societies / Memorial Sloan Kettering Cancer Center I performed a two year head and neck surgery and oncology / endocrine fellowship that ended in 2016. Mi nombre es Rodrigo Arrangoiz, soy cirujano oncólogo / cirujano de tumores de cabeza y cuello / cirujano endocrino que trabaja Center for Advanced Surgical Oncology en Miami, Florida. Fui entrenado como cirujano en Michigan State University (2005 a 2010 ) donde fui jefe de residentes en 2010. Mi formación en oncología quirúrgica y e n tumores de cabeza y cuello se realizó en el Fox Chase Cancer Center en Filadelfia de 2010 a 2012. Al mismo tiempo, me sometí a una maestría en ciencias (investigación clínica para profesionales de la salud) en la Universidad de Drexel. A través de la Federación Internacional de Sociedades de Cabeza y Cuello / Memorial Sloan Kettering Cancer Center realicé una sub especialidad en cirugía de cabeza y cuello / cirugia endocrina de dos años que terminó en 2016.

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