UGT1A9 and gastric cancer: A more interesting finding is that patients who suffered severe forms of toxicity that have previously been known to be associated with any of the significant UGT1A polymorphisms all had the UGT1A9*22 polymorphism, which confers more importance to the UGT1A9*22 polymorphism as a predictive marker for gastric cancer patients at high risk for irinotecan toxicity.