Related Experiment Video
Updated: Apr 21, 2026
Validated Immunochemical Assay for Comprehensive Determination of the Human Epidermal Growth Factor Receptor 2 Released from and Bound to Cells
Published on: May 9, 2025
Human epidermal growth factor receptor 2 testing in primary breast cancer in the era of standardized testing: a
Wedad M Hanna1, Penny J Barnes2, Martin C Chang2
1Wedad M. Hanna and Sharon Nofech-Mozes, Sunnybrook Health Sciences Centre, University of Toronto; Wedad M. Hanna, Martin C. Chang, and Sharon Nofech-Mozes, University of Toronto; Martin C. Chang, Mount Sinai Hospital, Toronto; Susan J. Robertson, Ottawa General Hospital and University of Ottawa, Ottawa; Sandip K. SenGupta, Kingston General Hospital and Queen's University, Kingston, Ontario; Penny J. Barnes, Capital Health District Authority and Dalhousie University, Halifax, Nova Scotia; C. Blake Gilks, Vancouver General Hospital and University of British Columbia, Vancouver, British Columbia; Henrike Rees and Louise Quenneville, Saskatoon City Hospital and University of Saskatchewan, Saskatoon, Saskatchewan, Canada; and Anthony M. Magliocco, Esoteric Laboratory Services, Moffitt Cancer Center, Tampa, FL. wedad.hanna@sunnybrook.ca.
Purpose:
Therapies that target overexpression of human epidermal growth factor receptor 2 (HER2) rely on accurate and timely assessment of all patients with new diagnoses. This study examines HER2 testing of primary breast cancer tissue when performed with immunohistochemistry (IHC) and additional in situ hybridization (ISH) for negative cases (IHC 0/1+). The analysis focuses on the rate of false-negative HER2 tests, defined as IHC 0/1+ with an ISH ratio ≥ 2.0, in eight pathology centers across Canada.
Patients And Methods:
Whole sections of surgical resections or tissue microarrays (TMAs) from invasive breast carcinoma tissue were tested by both IHC and ISH using standardized local methods. Samples were scored by the local breast pathologist, and consecutive HER2-negative IHC results (IHC 0/1+) were compared with the corresponding fluorescence or silver ISH result.
Results:
Overall, 711 surgical excisions of primary breast cancer were analyzed by IHC and ISH; HER2 and chromosome 17 centromere (CEP17) counts were available in all cases. The overall rate of false-negative samples was 0.84% (six of 711 samples). Interpretable IHC and ISH scores were available in 1,212 cases from TMAs, and the overall rate of false-negative cases was 1.6% (16 of 978 cases).
Conclusion:
Our observation confirms that IHC is an adequate test to predict negative HER2 status in primary breast cancer in surgical excision specimens, even when different antibodies and IHC platforms are used. The study supports the American Society of Clinical Oncology/College of American Pathologists and Canadian testing algorithms of using IHC followed by ISH for equivocal cases.
