Immunohistochemical staining (IHC) can be used as a surrogate marker of gene-expression profiling in invasive breast cancer, utilising ER, PR, HER2 and Ki-67 protein expression to split patients into four different molecular phenotypes.17 Similar subtypes have been found in DCIS, but the prognostic significance of grouping DCIS into these subtypes is not yet clear. Here, ERBB2 is linked to ductal breast carcinoma in situ.