XRCC1 rs25487 and OGG1 rs1052133 are not associated with CCA per se, but susceptibility is increased in smokers carrying XRCC1 GG wild-type compared to non-smokers carrying XRCC1 GG wild-type, while CCA susceptibility was higher in GA heterozygous smokers (OR = 3.4, 95% CI = 1.60–7.28) [117]. Here, OGG1 is linked to cholangiocarcinoma.