ERBB2 and breast cancer: Gallen International Expert Consensus on the Primary Therapy of Early Breast Cancer 2013 [18] have both included a recommendation for consideration of adjuvant trastuzumab in pT1bN0M0 rather than pT1aN0M0 HER2-positive women, while the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines 2011 [19] held that the use of trastuzumab should be discussed with HER2-positive pT1a-bN0M0 patients.