Objective: To investigate the possible association of single nucleotide polymorphism (SNP) at the 41657C/T position and 4234G/C position of X-ray repair cross-complementing gene 2 (XRCC2) with susceptibility to esophageal squamous cell carcinoma (ESCC) and gastric cardiac adenocarcinoma (GCA) in a population of high incidence region, Ci county and She county of Hebei.
Methods: The genotypes of XRCC2 41657C/T and 4234G/C SNPs were detected by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) analysis in 330 ESCC patients, 254 GCA patients and 629 healthy controls.
Results: The genotype frequency of XRCC2 41657C/T in ESCC patients (67.8%, 26.4% and 5.8%) was significantly different from that in controls (68.8%, 28.8% and 2.4%; chi square was 7.43, P was 0.02). Compared with CC genotype, TT genotype significantly increased the risk of developing ESCC (OR=2.12, 95%CI: 1.03-4.35). The genotype (59.9%, 35.8% and 4.3%) and allelotype distributions ofXRCC2 41657C/T in GCA patients were significantly different from that in controls (chi square was 7.46 and 7.23, P was 0.02 and 0.01). Compared with CC genotype, CT genotype significantly increased the risk of developing GCA (OR=1.38, 95%CI: 1.01-1.89). The genotype and allelotype distributions of the 4234G/C SNPs in ESCC and GCA patients were not significantly different from that in controls (all P values were above 0.05). Compared with GG genotype, the CG and CC genotype of XRCC2 4234G/C did not show significant effect on the risk of developing ESCC and GCA. When the two XRCC2 SNPs were combined analyzed, the haplotype distribution in GCA patients was significantly different from that in controls (chi square was 13.28, P was less than 0.01). Compared with 41657C/4234G haplotype, 41657C/4234C and 41657T/4234G haplotypes significantly increased the risk of developing GCA (OR were 1.44 and 1.55, 95%CI were 1.06-1.95 and 1.18-2.02, respectively).
Conclusion: In high incidence region of Hebei province, we conclude that XRCC2 41657C/T polymorphism has a potential to be a susceptibility factor for ESCC and GCA while XRCC2 4234G/C polymorphism may not provide a useful marker to predict susceptibility to ESCC and GCA. However, the 41657C/4234C and 41657T/4234G haplotypes might increase the risk of developing GCA.