Based on the guidelines, DCIS was called ER‐ and/or PR‐positive if protein expression by IHC was expressed in ≥1% of cells; HER2 < 2+ was negative, 2+ was equivocal, and 3+ was positive; the biomarkers Ki67 and p53 were referred to as positive if expressed by ≥10% of cells. This evidence concerns the gene ERBB2 and ductal breast carcinoma in situ.