ESR1 and ductal breast carcinoma in situ: Univariable and multivariable conditional logistic regression models were used to examine the associations between the DCIS characteristics of interest (non-screen detection of DCIS, tumor size, positive margins, grade of DCIS, necrosis, architectural pattern, microcalcification, and estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status) and risk of IBC.