[The risk of adverse events of CPT- 11].

Irinotecan is a camptothecin analog used worldwide for a broad range of solid tumors, including colorectal cancer. It can cause severe adverse drug reactions, such as neutropenia or diarrhea. Recent pharmacogenetic studies on irinotecan have revealed the impact of UGT1A1 polymorphisms on severe adverse effects. The concurrence of UGT1A1*28 and UGT1A1*6, even when heterozygous, markedly alters the disposition of irinotecan, potentially increasing toxicity. For patients showing homozygosity for UGT1A1*28, *6 or compound heterozygosity for UGT1A1*6 and *28, dose reduction of irinotecan is strongly recommended. But dose reduction criteria or effect of dose reduction have not been clarified. If prediction accuracy of expression risk of adverse reaction improve, It is expected to be possible to appro- priate therapeutic indications and drug selection, dose setting.