ERBB2 and ductal breast carcinoma in situ: Moreover, these parameters classify more than 50% of DCIS in the high-risk group, however, the recurrence rate is currently around 15% with half of these being invasive.3 Therefore, a considerable percentage of DCIS patients are either over- or under-treated.4 Molecular characterisation based on hormonal receptors and HER2 status in addition to recently described multigene assays such as Oncotype DX DCIS score, have shown promising results to refine DCIS prognostic classification but the value of their application in routine practice remains unclear.5–9