By multivariate analysis, positive resection margin status (p = 0.007) and ER negativity (p = 0.03) in DCIS and omission of radiotherapy (p < 0.001) and ER and PR negativity (p = 0.001, p = 0.002) and high Ki-67 score (p = 0.04) in invasive cancer remained as significant factors predicting IBTR. This evidence concerns the gene ESR1 and ductal breast carcinoma in situ.