ESR1 and ductal breast carcinoma in situ: In the 66 patients with failure, the number of triple-negative (ER−PR−HER2−), luminal HER2-positive (ER/PR+HER2+), non-luminal HER2-positive (ER−PR−HER2+), luminal A (ER+PR+HER2−Ki-67 ≤ 20%) and luminal B (ER+PR+HER2−Ki-67 > 20%) subtypes in initial DCIS was 4, 7, 12, 35 and 8, respectively.