Stern et al. in Singapore Chinese also observed a positive association between XRCC1 codon 194Trp/Trp genotype and alcohol consumption (OR = 2.8, 95 % CI 1.0–8.1), and thought a role for reactive oxygen species as relevant genotoxins that might account for the effects of both smoking and alcohol on colorectal cancer risk [3]. Here, XRCC1 is linked to colorectal cancer.