ERBB2 and breast carcinoma: During the last 2 decades, the outcome of patients with early-stage ERBB2/HER2-positive breast cancer has markedly improved owing to new treatment strategies combining polychemotherapy and multiple ERBB2/HER2-targeted drugs.1,2,3,4,5,6,7,8,9,10 However, it is increasingly evident that many patients are overtreated by the recommended regimens, whereas others still experience metastatic relapse.