Several tumour markers have shown evidence of clinical usefulness and have been recommended for use in practice in breast cancer patients: CA 15-3, CA 27.29, carcinoembryonic antigen (CEA), oestrogen and progesterone receptors (ER, PR), human epidermal growth factor receptor 2 (HER-2), urokinase plasminogen activator (uPA), plasminogen activator inhibitor 1 (PAI-1) and certain multiparametre gene expression assays (Oncotype DX, MammaPrint, Rotterdam Signature) [1]. Here, ERBB2 is linked to breast cancer.