HER2 assessment for breast cancer

HER2: human epidermal growth factor receptor 2; IHC: immunohistochemistry; ISH: in situ hybridization.
* ISH should be recounted by an additional observer, blinded to previous ISH results; count should be at least 20 cells that include the area of invasive cancer with IHC 2+ staining.
¶ The predictive value of this finding of benefit from anti-HER2 therapy is unknown, and it therefore is also reasonable to omit anti-HER2 therapy.