When grouped by the type of recurrence, 27.0% of patients with LRR and 30.4% of patients with DM had a shift in HER2 status, while 42 out of 66 (63.6%) patients with contralateral breast cancer had change in HER2 status (P < 0.001, Table S1, Figure S4). This evidence concerns the gene ERBB2 and breast cancer.