The relevance of ER status and progesterone receptor (PR) status in DCIS to radiation therapy has not been well explored.<h4>Methods</h4>Patients undergoing breast-conserving surgery with or without radiation were grouped by ER and PR status and matched using rank-based Mahalanobis optimal matching with respect to lesion size and grade and patient age and race. This evidence concerns the gene ESR1 and ductal breast carcinoma in situ.