ERBB2 and breast cancer: The findings of this study support a growing body of evidence that is now consistently showing improved response rates and TTP when trastuzumab is continued beyond PD in HER2-positive advanced breast cancer (Stemmler et al, 2005; Bartsch et al, 2007; Fabi et al, 2008; Von Minckwitz et al, 2009; Blackwell et al, 2010).