ERBB2 and breast cancer: From these IHC markers, this case seems to be classified into a ‘luminal A’ type breast cancer according to the St Gallen International Expert Consensus, 2011 [25]; although Prat et al. recently suggested that ‘luminal A’ in immunohistochemical-based definition is hormone receptor positive/HER2 negative/Ki-67 less than 14%, and PgR more than 20% [26].