ERBB2 and neoplasm: Indeed, HER2-negative tumours which gave rise to HER2-low recurrences more frequently expressed oestrogen receptors (ER) (88.9% versus 73.8%, P = 0.008) and recurred later (90.3 ± 54.5 versus 68.2 ± 51.9 months; P = 0.002) than HER2-negative primary tumours which gave rise to recurrences with unchanged HER2-negative status.