Patients with HER2 positive tumours (defined as IHC 3+ and/or HER2 copy number ≥ 6 if FISH/CEP17 ratio <2 and/or HER2 copy number ≥ 4 if FISH/CEP17 ratio ≥ 2) are usually recommended for treatment with trastuzumab and other anti-HER2 therapies. Here, ERBB2 is linked to neoplasm.