Trastuzumab in association with chemotherapy as NST, for early or locally advanced HER2+ breast cancer, has been extensively investigated in phase II–III clinical trials in the last few years (Anton et al. 2011; Burstein et al. 2003; Coudert et al. 2007; Dawood et al. 2007; Gianni et al. 2010; Penault-Llorca et al. 2007; Petrelli et al. 2011; Pierga et al. 2010; Robidoux et al. 2010; Ruiz et al. 2008; Sanchez-Munoz et al. 2010; Sikov et al. 2009; Untch et al. 2010, 2012; Wildiers et al. 2011; Buzdar et al. 2005, 2007; Horiguchi et al. 2009; von Minckwitz et al. 2010; Valachis et al. 2011). This evidence concerns the gene ERBB2 and breast cancer.