Polymorphisms of DNA repair gene XRCC3 Thr241Met and risk of gastric cancer in a Chinese population

Mammalian cells are constantly exposed to a wide variety of genotoxic agents from both endogenous and exogenous sources. Genetic variability in DNA repair may contribute to human cancer risk. In this population-based case-control study in China, we tested the hypothesis that a C to T variant (Thr241Met) of DNA repair gene XRCC3 (X-ray repair cross-complementing group 3) is associated with risk of developing gastric cancer. We genotyped for this variant using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) in 188 histologically confirmed gastric cancer patients and 166 frequency-matched cancer-free controls. The XRCC3 genotype and allele frequencies were not significantly different between cases and controls (P = 0.99 for genotype; P = 0.76 for allele). The XRCC3 24 1 Met allele frequency (4.8%) was significantly lower in healthy Chinese controls than previously reported healthy US Caucasian controls (38.9%). Compared with the XRCC3 241Thr/Thr genotype, the variant XRCC3241Thr/Met and Met/Met genotypes were not associated with an increased risk of gastric cancer (adjusted odds ratio (ORa), 1.06; 95% confidence interval (CI), 0.52-2.16). These findings suggest that polymorphisms of XRCC3 Thr241Met may not play a role in the etiology of gastric cancer. Further studies with a larger number of subjects and simultaneous measurement of different polymorphisms in DNA repair genes in the same pathway are needed to confirm these findings. (C) 2003 Elsevier Ireland Ltd. All rights reserved.