In addition, DCIS lesions that were positive for ER staining were also more likely to be PR+ (P = 3.3×10−22), whereas ER- DCIS lesions had moderate or high Ki-67 staining (P = 2.3×10−10 and P = 4.3×10−8, respectively) (Figure 2A and Table S1 in File S1). This evidence concerns the gene ESR1 and ductal breast carcinoma in situ.