We have previously shown that the administration of 6 cycles of trastuzumab in patients with HER2-negative early breast cancer harbouring CK-19mRNA-positive CTCs both before and after the completion of adjuvant chemotherapy, was associated with a significantly lower incidence of clinical relapses and a longer disease-free survival compared to patients who received the standard of care [38]. Here, ERBB2 is linked to breast carcinoma.