ERBB2 and ductal breast carcinoma in situ: Treatment is by mastectomy, or lumpectomy with or without adjuvant radiotherapy.6 Factors such as young patient age, large tumour size,7 positive margins, comedo necrosis and high-nuclear grade8 are associated with a higher risk of recurrence with some emerging data suggesting that ERBB2-amplified (HER2) DCIS could present a higher risk of recurrence.9 The Van Nuys Prognostic Index is a popular risk assessment tool combining patient age, lesion size, nuclear grade and margin status for treatment decisions.10