Stern et al. in an American population found that the association between ever smoking and colorectal adenoma risk was only observed among subjects who carried the XRCC1 codon 194 Arg/Arg and codon 399 Arg/Arg or 399Arg/Gln genotypes (test of interaction, P = 0.048) [4]. The gene discussed is XRCC1; the disease is colorectal adenoma.