ERBB2 and breast cancer: Although the treatment outcome of HER2+ breast cancer patients has been significantly improved with anti-HER2 agents, it is approximated that one in four early-stage breast cancer patients treated with trastuzumab will relapse within a decade [16] and only 18 months of median progression-free survival was recorded when patients have a triple combination of pertuzumab, trastuzumab and docetaxel [17].