ERBB2 and ductal breast carcinoma in situ: Size-matched IDC-DCIS was more likely than pure IDC to be screen detected (P=0.03), to occur in pre-menopausal women (P=0.002), and to be either ER-positive (P=0.002) or HER2-positive (P<0.0005), but less likely to be treated with breast-conserving surgery (P=0.004).