It is known that DCIS is recognized as a precursor of IDC.[64] To study the progression routes of four subtypes of IDC, the DCIS_adjIDC samples were divided correspondingly into pre‐luminal A (n = 8), pre‐luminal B (n = 18), pre‐HER2‐enriched (n = 5), and pre‐TNBC (n = 2) (Figure S7B, Supporting Information). Here, ERBB2 is linked to ductal breast carcinoma in situ.