ERBB2 and neoplasm: Cellular markers of the tumour biology such as IHC positivity for estrogene receptor (ER), progesteron recepetor (PR), epidermal growth factor receptor 2 (HER-2), cytokeratin 5/6, epidermal growth factor receptor 1 (EGFR) and for cell proliferation (Ki67) are currently the gold standard for therapy stratification, but require considerable laboratory work and are prone to subjective bias.