ERBB2 and ductal breast carcinoma in situ: Mastectomy rates were higher in IBC+DCIS compared to IBC (53.6% versus 41.0%, p < 0.001).<h4>Conclusion</h4>Pathologic complete response of DCIS occurred in 52.0% of HER2-positive IBC patients and was associated with ER-negative IBC and more recent years of diagnosis.