In recent years, several novel IHC methods to quantify HER2 levels are being investigated, including the quantum dot (QD)-based detection method [9], immunofluorescence method to quantify single-cell levels [10], IHC technique with QD-conjugated trastuzumab [11], quantitative IHC (qIHC) [12], HERmark Breast Cancer assay [13], and quantitative immunofluorescence AQUA method [14, 15]. This evidence concerns the gene ERBB2 and breast cancer.