In addition, there was a tendency for CYP1A2*1A/*1A genotypes to reduce the risk of CCA compared with CYP1A2*1F/*1F genotypes (OR = 0.28, 95% CI = 0.08~0.94, p = 0.039), but this finding was only observed in male patients. Here, CYP1A2 is linked to cholangiocarcinoma.