Importantly, by comparing the expression of promising DCIS risk biomarkers (Ki-67, p53 and p16) among different DCIS subgroups, our results suggest the existence of a highly-aggressive DCIS subgroup, which had the same molecular subtype as the adjacent IDC but not the same subtype as the adjacent normal terminal duct lobular units (TDLU) (Table 4). This evidence concerns the gene MKI67 and ductal breast carcinoma in situ.