XRCC1 and cancer: Several common and putatively functional single nucleotide polymorphisms (SNPs) of ERCC1, XRCC1, and XRCC3 have been identified, of which ERCC1 C118T and ERCC1 C8092A affect ERCC1 mRNA expression, whereas XRCC1 Arg194Trp and XRCC1 Arg399Gln, and XRCC3 Thr241Met are associated with suboptimal DNA repair capacity [9,11], and with an altered risk of several types of cancer [12–15].