XRCC1 and esophagitis: Consistent with existing studies demonstrating the associations of radiotherapy-associated toxicity with SNPs in genes in the DNA damage repair, oxidative reduction and metabolic pathways, we identified SNPs in X-ray repair cross-complementing 1 (XRCC1, rs25487, c.1196A>G; OR=2.31 [95%CI, 1.0-5.56]; P=0.05) and XRCC5 (rs3835, c.2110-2408G>A; OR=3.59 [95% CI, 0.93-12.96]; P=0.03), which conferred increased risks of radiation-induced pneumonitis and esophagitis, respectively (Figures 7A, B).