Manganese superoxide dismutase polymorphism and prostate cancer risk: a meta-analysis

Objective

MnSOD plays a vital role in carcinogenesis, partly in that it converts superoxide radical to oxygen and hydrogen peroxide. The conflicting results of studies on the role of MnSOD polymorphism (Val−9Ala) with the risk of prostate cancer encouraged us to perform a meta-analysis to examine the association.

Methods

A comprehensive search was conducted to examine all the eligible studies of MnSOD polymorphism and prostate cancer risk. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. The pooled estimates of ORs were computed using the fixed-effects model or random- effects model.

Results

Ten eligible studies, including 4 608 cases and 5 861 controls, were included in this meta-analysis. Overall, individuals with Ala/Ala and Ala/Val genotypes have an increased risk of prostate cancer, compared with those carrying the Val/Val genotype (Ala/Ala vs. Val/Val: OR=1.13; 95% CI=1.02∼1.25; P = 0.020, P_{heterogeneity}=0.370; Ala/Val vs. Val/Val: OR=1.14; 95% CI=1.04∼1.25; P = 0.004, P_{heterogeneity}=0.940). This significant association was also found in a dominant model with −9Ala allele (Ala/Ala+Ala/Val vs. Val/Val: OR=1.12; 95% CI: 1.03∼1.22; P = 0.009, P_{heterogeneity}=0.64). In the subgroup by ethnicity, it was observed that significantly elevated prostate cancer risk was associated with −9Ala allele in Caucasians (Ala/Ala vs. Val/Val: OR=1.14; 95% CI=1.03∼1.27; P = 0.01, P_{heterogeneity}=0.31; Ala/Val vs. Val/Val: OR=1.14; 95% CI=1.04∼1.24; P = 0.006, P_{heterogeneity}=0.87) but not in African-Americans. Furthermore, this meta-analysis showed that the −9Ala allele was associated with both nonaggressive and aggressive prostate cancer risks.

Conclusion

Our meta-analysis suggests that MnSOD Val−9Ala polymorphism is associated with prostate cancer risk, especially in Caucasians.