Relationship between polymorphism in the manganese superoxide dismutase gene and breast cancer.

Manganese superoxide dismutase (MnSOD) acts as an antioxidant and protects cells from the harmful effects of reactive oxygen species. We investigated the relationship between the MnSOD Ala-9Val polymorphism and breast cancer. Genotypes of 250 cases and 330 controls were determined by use of PCR-RFLP. Compared with the MnSOD Val/Val genotype, the MnSOD Val/Ala or MnSOD Ala/Ala genotype was not significantly associated with the overall risk for breast cancer. The risk increased in women with MnSOD Ala allele-containing genotypes as well as higher level of education (Ala/Ala: OR, 6.00; 95% CI, 1.02-35.33), BMI >or= 25 kg/m(2) (Val/Ala: OR, 1.74; 95% CI, 1.10-2.76), late age at first pregnancy (Val/Ala: OR, 1.52; 95% CI, 1.01-2.42), and premenopausal status (Val/Ala: OR, 1.78; 95% CI, 1.03-3.10). In conclusion, the MnSOD Ala-9Val polymorphism may contribute to an increased risk for breast cancer development, particularly in the presence of a higher level of education, high BMI, late age at first pregnancy, and premenopausal status.