BACKGROUND:

Exogenous reactive oxygen species (ROS) induces DNA damage. Manganese superoxide dismutase (SOD2) catalyzes the dismutation of superoxide radicals, a major type of ROS, into hydrogen peroxide. p53 is a tumor suppressor gene, and X-ray cross-complementing group 1 (XRCC1) is involved in the base-excision repair of ROS-induced DNA damage.

METHODS:

The authors investigated whether the SOD2 Ala16Val polymorphism modifies the associations between p53 Arg72Pro and XRCC1 Arg399Gln polymorphisms and the risk of nonsmall cell lung carcinoma (NSCLC) in a case-control study of 935 Caucasian patients with NSCLC and 1233 healthy control participants. The results were analyzed using logistic regression models that were adjusted for possible confounding variables.

RESULTS:

There was no association between p53 or XRCC1 polymorphism and NSCLC risk for individuals with SOD2 Ala/Ala or Ala/Val genotype. For individuals with the SOD2 Val/Val genotype, greater risks were found in association with p53 (variant Pro allele vs. Arg/Arg), XRCC1 (variant Gln allele vs. Arg/Arg), and the combination of the two polymorphisms ("double variant" vs. "double wild type"), with the adjusted odds ratios (ORs) of 1.84 (95% confidence interval [95% CI], 1.20-2.82), 1.39 (95% CI, 0.98-2.21), and 2.54 (95% CI, 1.38-4.68), respectively. Furthermore, the greater risk for the double variant of p53 and XRCC1 in the SOD2 Val/Val genotype group was specific only for patients with adenocarcinoma and not for patients with squamous cell carcinoma, with adjusted ORs of 3.31 (95% CI, 1.68-6.51) and 0.69 (95% CI, 0.24-2.02), respectively.

CONCLUSIONS:

The SOD2 Val/Val genotype may increase the risk of NSCLC carried by XRCC1 and p53 polymorphisms, particularly for adenocarcinoma.