ERBB2 and neoplasm: Luminal B tumours appear at a frequency of 20–30% and show a worse prognosis; Her2+ (12–20%) are aggressive tumours yet respond well to treatments directed at inhibiting this receptor, such as herceptin (trastuzumab); and TNBC, which make up the remaining 15–20%, show the worse prognosis and are the most difficult to treat [11].