ERBB2 and breast carcinoma: The management of patients with breast carcinoma currently uses the following prognostic factors: Disease stage (which takes into account axillary lymph node involvement, tumour size and distant tumour dissemination), degree of differentiation (tumour grade), histological type, proliferation index and receptor status [progesterone receptor (PR), oestrogen receptor (ER) and receptor 2 of the human epidermal growth factor (HER2)] of the primary tumours (1–2).