Finally, in order to test whether individual polymorphisms in DNA repair genes might interact and modify the risk of developing lung cancer, ORs were estimated for each pair of the studied polymorphisms (XPC PAT, XPD Asp312Asn, XPD Lys751Gln, XRCC1 Arg399Gln and XRCC3 Thr241Met). Here, XPC is linked to lung cancer.