However, the overall response rate of IHC 2+ amplified BC in our study was in line with others27 using either the updated guidelines3 (Groups 1 + 3) or the 2013 ASCO/CAP recommendations.44 In order to report on sufficient cases with these uncommon patterns of HER2 expression, the cancers in this series were collected from several centres. Here, ERBB2 is linked to breast cancer.