In a study of 1600 colorectal cancer patients and 2500 unaffected siblings, the variation in 4 UGT genes (UGT1A3, UGT1A6, UGT2B4, and UGT2B15) modified risk of colorectal cancer either independently of interactively with nonsteroidal anti-inflammatory use (79). This evidence concerns the gene UGT1A3 and colorectal cancer.