UGT1A4 (p = 0.007) and UGT2B7 mRNA expression (p = 0.001) both showed a similar decrease in mRNA expression pattern as UGT1A1 in breast tumor specimens; however, the mean mRNA levels of UGT1A1 was most significantly decreased in breast cancers compared to normal controls (p = 0.0006) compared to UGT1A4 (p = 0.0068) and UGT2B7 (p = 0.0014). This evidence concerns the gene UGT1A4 and breast cancer.