ESR1 and ductal breast carcinoma in situ: We examined the relationships between clinicopathologic factors including age, DCIS architecture, Van Nuys classification, grade, comedo necrosis, apocrine features, TIL, CD8+ lymphocytes, healing, estrogen receptor and HER2 positivity, and IHC‐based subtypes [luminal, luminal‐HER2, HER2‐positive, triple negative (TN)].