UGT1A9 and metastatic colorectal cancer: The aim of this study was to compare the efficacy, safety and survival rate of a treatment regimen comprising capecitabine plus irinotecan (XELIRI) to those of a standard regimen comprising leucovorin, fluorouracil and irinotecan (FOLFIRI), to determine the correlation among the inherited genetic variations in UGT1A1, UGT1A7 and UGT1A9. A total of 84 consecutive patients with histologically confirmed metastatic colorectal cancer (mCRC) were included in the study.