XRCC3 and lung cancer: In order to examine if genetic polymorphisms in DNA repair genes implicated in NER, BER and DSBR pathways are associated with lung cancer risk, we have studied five polymorphisms in four genes (XPC, XPD, XRCC1, XRCC3) in 516 cases and 533 controls of a Caucasian population of Northern Spain, historically highly exposed to tobacco.