ERBB2 and breast neoplasm: Of interest, somatic sequencing showed that HER2-positive breast cancer is a heterogeneous group, and HER2 amplification is found in all breast tumour subtype profiles.11 HER2-positive breast cancers do not per se represent a homogeneous subtype, but are actually distributed along the whole breast cancer spectrum, from oestrogen receptor-positive luminal to oestrogen receptor-negative basal phenotype, with genome alterations in accordance with these phenotypes.