The introduction of the humanized anti‐HER2 monoclonal antibody (mAb) trastuzumab in combination with chemotherapy has improved both the relapse‐free survival (RFS) and overall survival (OS) of primary and metastatic HER2‐positive BC patients (Joensuu et al., 2006; Piccart‐Gebhart et al., 2005; Pupa et al., 2005; Romond et al., 2005; Slamon et al., 2001). Here, ERBB2 is linked to breast cancer.