In the clinic, although intrinsic breast cancer subtypes defined by pathologic classification of ER, PR, HER2, and Ki-67 status facilitate the development of precise treatment approaches, the use of these methods remains far from perfect due to subjectivity among pathologists in interpreting test results, diversity of antibody quality, and lack of standardize immunohistochemical protocols among hospitals. This evidence concerns the gene ERBB2 and breast carcinoma.