ERBB2 and breast cancer: Furthermore, when combined with selected molecular markers, including the immunohistochemical detection of hormone receptors, HER2 and the proliferation marker Ki67 and copy number quantification of the HER2 locus by FISH, it provides adequate information for the therapeutic management of the tumors, as well as reasonable prognostic value, probably not inferior to molecular classifications for the most common types of breast cancer [8-11].