Objective: To study the polymorphisms of DNA repair gene XRCC3 and the relationship between genetic variations and susceptibility to lung cancer.
Methods: A case-control study of 291 patients with lung cancer and 273 cancer-free subjects as a control group was conducted from September 2006 to January 2007 to detect XRCC3 polymorphisms at loci. Genotypes of XRCC3 were analyzed by real time PCR using Taqman probes.
Results: Compared with never smoking subjects with wild homozygous genotype (Thr/Thr), smokers with the same genotytpe (Thr/Thr) had increased risk of lung cancer, adjusted odds ratio (OR) was 2.467 (95% CI: 1.49 - 4.08, P < 0.001). Smokers with the heterozygous genotype (Thr/Met) also had increased risk of lung cancer, adjusted OR was 2.283 (95% CI: 1.21 - 6.60, P < 0.05). XRCC3 codon 241 homozygous genotype (Thr/Thr) and pack-years of smoking less than 30 had a weak protective effect on adenocarcinoma (OR = 0.49, 95% CI: 0.26 - 0.93, P < 0.05). Allel Met of XRCC3 codon 241 and smoking conferred an increased risk of squamous cell carcinoma (OR = 9.69, 95% CI: 3.27 - 28.72, P < 0.01). Those with allel Met of XRCC3 codon 241 and pack-years of smoking less than 30 or more than 30 had different risk of squamous cell carcinoma, the OR was 8.00 (95% CI: 1.97 - 32.52, P < 0.01), and 11.67 (95% CI: 2.98 - 45.73, P < 0.01) respectively.
Conclusion: The results demonstrated that genetic polymorphism of XRCC3 DNA repair gene may contribute to the susceptibility to lung cancer and have synergistic effect with smoking.