Furthermore, the mean mRNA expression levels of UGT1A4 (Tumor: 0.8 ± 0.3; Normal: 3.6 ± 1.2, p = 0.007), UGT1A10 (Tumor: 7.5 ± 1.3; Normal: 8.8 ± 2.4, p = 0.6), and UGT2B7 (Tumor: 0.8 ± 0.3; Normal: 4.9 ± 1.5, p = 0.001) was significantly down-regulated in breast tumors as compared to normal breast tissues. This evidence concerns the gene UGT1A4 and breast neoplasm.