ERBB2 and breast cancer: In addition, HER2-driven tumour cell dormancy has been previously demonstrated [41, 42] and might explain the long-term natural history of HER2-low BC in light of higher ERBB2 expression compared to HER2 0 BC [7] and lack of prolonged adjuvant therapy as in HER2-positive BC, that might eradicate or at least maintain dormancy [42].