Carriership of the variant alleles of some of the polymorphisms of genes coding for proteins of DNA repair that are associated with decreased mRNA and protein levels – namely, ERCC1 (C8092A), XRCC1 (Arg399Gln) and XPD (Lys751Gln), may confer lower risk for development of resistance to platinum-based therapy in some tumours (non-small-cell lung cancer, gastric carcinoma) (25, 42). This evidence concerns the gene XRCC1 and non-small cell lung carcinoma.