Testing for HER2 in Breast Cancer: Current Pathology Challenges Faced in Canada

Abstract

This review is designed to highlight several key challenges in the diagnosis of human epidermal growth factor receptor 2 (HER2)–positive breast cancer currently faced by pathologists in Canada: (1) Pre-analysis issues affecting the accuracy of HER2 testing in non-excision sample types: core-needle biopsies, effusion samples, fine-needle aspirates, and bone metastases (2) HER2 testing of core-needle biopsies compared with surgical specimens (3) Criteria for retesting HER2 status upon disease recurrence. Literature searches for each topic were carried out using the MEDLINE, Embase, International Pharmaceutical Abstracts, and biosis databases. In addition, the congress databases of the American Society of Clinical Oncology (2005–2011) and the San Antonio Breast Cancer Symposium (2007–2011) were searched for relevant abstracts. All authors are expert breast pathologists with extensive experience of HER2 testing, and several participated in the development of Canadian HER2 testing guidelines. For each topic, the authors present an evaluation of the current data available for the guidance of pathology practice, with recommendations for the optimization or improvement of HER2 testing practice.

The Human Epidermal Growth Factor Receptor 2 Screening Tests for Breast Cancer Suggested by the New Updated Recommendation of the American Society of Clinical Oncology/College of American Pathologists Will Involve a Rise of the In-Situ Hybridization Tests for the European Laboratories of Pathology

“…The main critic of our study is the selection of patients: 28 cases were discarded, particularly because a technical defect potentially causes false HER2 results, well documented in the literature such as crush artefacts or retraction and small size of tumoral sample [ 20 ]. Nevertheless, we did not have the pretention to give epidemiological data and the aim of this study was only to evaluate the impact of the new 2013 recommendation in our European practice.…”

ER, PR and HER2 testing in breast cancer

“…When IHC or FISH is used to determine HER2 status, high concordance between the results obtained from core biopsy samples and in excisional specimens is generally seen (85%e99%). 21 The IHC concordance appears to be associated with initial IHC score obtained for the core biopsy. D'Alfonso and colleagues reported 100% concordance between the HER2 status of core biopsy and corresponding surgical excision specimen in the IHC 3þ group.…”

“…The discordance rate between original HER2 status of the primary tumour and metastasis without neoadjuvant or adjuvant treatments have been reported as between 3.0% and 13.6% in several small studies. 21 The changes can be either direction. Primary tumour and metastatic lymph nodes showed concordance rates of 95% for HER2 negative primary tumours and 83.3% for HER2 positive primary tumours.…”

Standardized Assessment of Ki-67 in Breast Cancer Patients Using Virtual Slides and an Automated Analyzer in Comparison to Central/Local Pathological Assessments

“…However, there are certain limitations to the Ki-67 index, including standardization of a measurement method, reproducibility of measurement results, and establishment of cut-off values [13][14][15][16]. The core needle biopsy (CNB) procedure is almost as accurate as immunohistochemical analysis of surgical specimens for breast cancer diagnosis and is now widely accepted as the standard diagnostic procedure [17][18][19][20]. However, previous reports have shown variations in Ki-67 expression among pretreatment CNB specimens and post-treatment surgical specimens [21][22][23].…”