NAT2 and intrahepatic cholangiocarcinoma: Similarly, we constructed a prognostic risk score model for calculating ICC risk as follows: risk score of ICC (RS_ICC) = (−1.1988 × expression value of CYP26A1) + (0.1217 × expression value of NAT2) + (0.2819 × expression value of UGT2B10), with AIC value =100.3791.