Association between Genetic Polymorphisms in Superoxide Dismutase Gene Family and Risk of Gastric Cancer.

To determine the association between the SOD1 (Ins/Del), SOD2 (rs2758339, rs5746136), and SOD3 (rs2536512) polymorphisms and the risk of gastric cancer the present study performed. This is a case-control study, including 159 patients with gastric cancer and 242 healthy controls. All subjects were Persian Muslims living in Shiraz (south west Iran). Frequency matching by age and gender was performed. Genomic DNA was extracted from whole blood. Genotypes of the study polymorphism were determined using polymerase chain reaction based methods. The SOD1 Ins/Del and SOD3 rs2536512 polymorphisms did not appear to have relationship with gastric cancer risk. Both SOD2 polymorphisms (rs2758339, rs5746136) showed significant association with the risk of gastric cancer, under assumption that the variant alleles act as dominant alleles. There was significant association between smoking habit and the risk of gastric cancer (OR = 2.54, 95% CI = 1.61-4.02, P < 0.001). Smoker individuals having two putative high-risk genotypes showed elevated risk of gastric cancer compared with nonsmokers without high-risk genotypes, (OR = 5.75, 95% CI = 1.59-20.6, P = 0.007). Assuming that smoking habit and the genotypes are independent risk factors, there was a significant linear trend for the numbers of risk factors and gastric cancer risk (χ2 = 22.9, P < 0.001). This study indicates that the SOD2 polymorphism (rs2758339, rs5746136) is associated with increased risk of gastric cancer, especially in smoker individuals.