ERBB2 and ductal breast carcinoma in situ: In the TILS ≥ 40% group, 83.7% of DCIS had HER2+ expression (HR + HER2+:25.6%; HR-HER2+:58.1%); 80% of DCIS-Mi HER2+ expression (HR + HER2+: 23.3%; HR-HER2+: 56.5%).