Immunohistochemical HER2 Status Evaluation in Breast Cancer Pathology Samples: A Multicenter, Parallel-Design Concordance Study

Abstract

Objective: As patients with increased human epidermal growth factor receptor (HER2) overexpression are more likely to benefit from trastuzumab treatment, the accuracy of HER2 receptor status in breast cancer patients is significant for appropriate disease management. However, this assessment is not harmonized and results may be highly variable between centers. The aim of this study was to investigate the degree of interlaboratory variability in the results of HER2 expression reported by 5 participating centers and to assess the concordance between these centers and a reference laboratory.