INTRODUCTION: One of the several metabolic pathways involved in breast carcinogenesis is the human polymorphism in the mitochondrial targeting sequence Ala-9Val of the manganese superoxide dismutase (MnSOD) gene, which has been previously associated with increased risk of breast cancer in females. Since there is no previous report on this polymorphism in male breast cancer, the objective of this study is to analyze MnSOD polymorphism in a population of males and females with breast cancer from the southernmost state of Brazil, compared to healthy controls. METHODS: A case-control study of one hundred patients affected by breast cancer (11 men and 89 women) and 370 healthy age-adjusted database controls was performed. DNA was extracted from paraffin-embedded tumoral tissue. MnSOD polymorphism was determined by PCR-RFLP techniques using restriction enzyme Hae III. Chi-square test was used to compare MnSOD frequency distribution. RESULTS: MnSOD genotypic frequencies in all patients with breast cancer were AA = 15%; AV = 56%; VV = 29% and controls AA = 6.5%; AV = 68.1% and VV = 25.4%. Both male and female patients with breast cancer presented significantly higher AA frequencies compared to controls (p = 0.035), suggesting strong association of this genotype with breast cancer. A 2.15-fold (95% confidence interval [CI] 1.393-4.541) risk of breast cancer was found among individuals carrying the MnSOD AA allele-containing genotypes compared with the MnSOD VV and AV genotypes. DISCUSSION: These results confirm the already established association of MnSOD AA genotype with female breast cancer and further indicate a similar frequency distribution and increased risk in the male population.
Male breast cancer; MnSOD; Gene polymorphism; SOD2; Oxidative stress
