Lack of association between MnSOD Val16Ala polymorphism and breast cancer risk: a meta-analysis involving 58,448 subjects.

Published data on the association between MnSOD Val16Ala polymorphism and breast cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Medline, PubMed, Embase, and Web of Science were searched. Crude ORs with 95% CIs were used to assess the strength of association between the MnSOD Val16Ala polymorphism and breast cancer risk. The pooled ORs were performed for co-dominant model (Val/Ala vs. Val/Val, Ala/Ala vs. Val/Val), dominant model (Ala/Ala + Val/Ala vs. Val/Val), and recessive model (Ala/Ala vs. Val/Ala + Val/Val), respectively. A total of 32 studies including 26,022 cases and 32,426 controls were involved in this meta-analysis. Overall, no significant associations were found between MnSOD Val16Ala polymorphism and breast cancer risk when all studies pooled into the meta-analysis (Val/Ala vs. Val/Val: OR = 1.022, 95% CI = 0.981-1.064; Ala/Ala vs. Val/Val: OR = 1.006, 95% CI = 0.934-1.083; dominant model: OR = 1.013, 95% CI = 0.962-1.066; and recessive model: OR = 0.985, 95% CI = 0.931-1.042). In the subgroup analysis by ethnicity or study design, still no significant associations were found for all comparison models. In conclusion, this meta-analysis suggests that the MnSOD Val16Ala polymorphism may be not associated with breast cancer development. However, large sample and representative population-based studies with homogeneous breast cancer patients and well-matched controls are warranted to confirm this finding.