In an analysis of 103 patients with stage IIIA–IV lung cancer, those with one or two variant alleles at XRCC1 (Arg399Gln) or XPD (Asp312Asn) showed poorer OS compared with those carrying homozygous wild-type alleles (P = 0.07 and P = 0.003, respectively). Here, XRCC1 is linked to lung cancer.