ERBB2 and breast cancer: The update ASCO/CAP guideline for breast cancer has adopted the criteria of equivocal for HER2 amplification, that is, [HER2/CEP17 ratio < 2.0] and absolute value of [average HER2 copy number ≥ 4.0 and < 6.0 signals/cell] by HER2-DISH [19].