This is also reflected in studies looking at gene expression analysis, with cancers belonging to the HER2-enriched intrinsic subtype showing higher pCR rates and the patients showing an improved event-free survival than those with non-HER2-enriched tumours.33 Supporting this, and in line with our results, Krystel-Whittemore et al. reported that BC with IHC 3+ HER2 protein over-expression showed significantly higher pCR rate (67%) compared to BC with IHC 2+ and HER2 gene amplification (17%).27 Here, ERBB2 is linked to cancer.