CYP2A6 appears to activate several procarcinogens such as hexamethylphosphoramide, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and aflatoxin B1, and studies have shown that the CYP2A6 activity is associated with pancreatic cancer [46] and colorectal cancer [25]. This evidence concerns the gene CYP2A6 and colorectal cancer.