Sagara Y, et al. - Using data from a retrospective multi-institutional cohort of JBCRG-C03, a substudy was performed to examine whether the basal human epidermal growth factor receptor 2 (HER2) subtype of breast cancer has distinguished characteristics. One hundred eighty-four eligible patients were identified who received concurrent neo-adjuvant chemotherapy (NAC) with trastuzumab for hormone receptor-negative and HER2-positive breast cancer between 2001 and 2011. According to the findings obtained, basal HER2 phenotype exhibited poor disease-free survival (DFS), but equivalent pathologic complete response (pCR) rate after concurrent neo-adjuvant chemotherapy with trastuzumab. Even for cases that achieved adequate clinical response after NAC, a different treatment approach to basal-HER2 type was required.