DCIS intraepithelial lymphocyte, CD3+ T-cell, CD3+CD8− T-cell, CD3+FOXP3+ T-cell and CD8+Ki67+ T-cell density was significantly higher in HER2-positive DCIS compared to HER2-negative DCIS (Supplementary Fig. 1B). This evidence concerns the gene MKI67 and ductal breast carcinoma in situ.