ERBB2 and breast cancer: Triple-negative breast cancer (TNBC) refers to breast cancer phenotype where the estrogen and progesterone receptors are negative [by immunohistochemistry (IHC)] with lack of overexpression of human epidermal growth factor receptor 2 (HER2) [by IHC], or the absence of HER2 neu amplification [by fluorescence in situ hybridization technique] [3].