The HERmark report is based on reference data from 1090 samples in both adjuvant and metastatic breast cancer patient cohorts. The patient data represent a large sample size and covers a broad range of HER-2 protein levels. Therefore, the HERmark Breast Cancer Assay can accurately quantify HER-2 total protein expression in most properly formalin-fixed paraffin-embedded (FFPE) breast cancer tumor tissue specimens.