The addition of trastuzumab in those patients with HER2-positive tumours [HER2 immunohistochemistry (IHC) score 3+, or HER2 IHC 2+ and fluorescent in situ hybridisation (FISH/ISH)-positive] is required, secondary to the demonstrated survival benefit in the TOGA Trial [30]. The gene discussed is ERBB2; the disease is neoplasm.