Fig. 1

Screening process for analyzed patients. Of 2783 colorectal cancer patients available for screening, 1615 patients who did not received irinotecan-based chemotherapy and 497 patients without complete clinical information and blood samples were excluded. Of the 661 patients included in this analysis, 71 patients received irinotecan plus fluorouracil-based chemotherapy, while the other 590 patients received irinotecan plus fluorouracil-based chemotherapy