Assessment ofERBB2/HER2Status inHER2-Equivocal Breast Cancers by FISH and 2013/2014 ASCO-CAP Guidelines

Importance

The 2013/2014 American Society of Clinical Oncology and College of American Pathologists (ASCO-CAP) guidelines forHER2testing by fluorescence in situ hybridization (FISH) designated an “equivocal” category (averageHER2copies per tumor cell ≥4-6 withHER2/CEP17 ratio <2.0) to be resolved as negative or positive by assessments with alternative control probes. Approximately 4% to 12% of all invasive breast...