Calibration of immunohistochemistry for assessment of HER2 in breast cancer: results of the French Multicentre GEFPICS* Study

Abstract

This study showed that a high accuracy of IHC could be obtained for the determination of HER2 status in all laboratories using their in-house IHC technique, provided that a calibration process was performed. Antigen retrieval procedure, high dilutions of anti-HER2 antibody and the use of specific controls were crucial for HER2-IHC calibration. A 95% accuracy rate of IHC, using FISH as gold standard, was obtained by considering immunolabelling HER2-IHC results as a continuous variable, and taking 60% invasive stained cells as the cut-off for HER2 over-expression.