ERBB2 and ductal breast carcinoma in situ: The risk factors for developing DM in DCIS include younger age (≤40 years), lymph node metastasis, microinvasion, necrosis, little or no expression of hormone receptors, poor differentiation, previous or simultaneous invasive locoregional recurrence, positive HER2 expression, and high Ki-67 staining (>10%) (1, 5, 41, 42).