FPN1 expression in IDC lesions was significantly higher in ER negative (p = 0.018) and in HER2 positive cases (p = 0.001) in epithelial cells, whereas in DCIS lesions FPN1 expression was only associated with negative ER status in macrophages (p = 0.033). Here, ERBB2 is linked to ductal breast carcinoma in situ.