Some studies identified a correlation between HER2-positive DCIS and increased ipsilateral in situ recurrence risk [7, 8], whereas others observed an association between HER2-positive DCIS and increased ipsilateral invasive recurrence risk (Table 2) [7, 8, 11, 12, 26–34]. The gene discussed is ERBB2; the disease is ductal breast carcinoma in situ.