ESR1 and ductal breast carcinoma in situ: Cox regression showed in Fig. 3 there were significant differences between HRs of DCISM versus DCIS for CSS in subgroups of age (<40 years or ≥40 years), race (white or black), gradeII, grade III and UD, ER (positive or negative), PR (positive or negative), no lymph node, surgery (yes or no) and radiotherapy (yes or no).