The rs2234694 and 50 bp Insertion/Deletion polymorphisms of the SOD1 gene are associated with breast cancer risk in a Mexican population

OBJECTIVE: The rs2234694 and 50 bp insertion/deletion (Ins/Del) polymorphisms of the SOD1 gene have been shown to be associated with many diseases, but in breast cancer (BC) their association has not been detected. The purpose of this study was to determine the frequency and association of SOD1 gene polymorphisms (rs2234694 and 50 bp Ins/Del) in BC patients in the Mexican population. MATERIALS AND METHODS: The SOD1 polymorphisms were determined by Polymerase Chain Reaction (PCR) in Mexican healthy subjects and BC patients. RESULTS: The rs2234694 polymorphism was associated with BC susceptibility when BC patients and the control group were compared for the AC genotype (p<0.0001), the AC/CC genotype (dominant model: p<0.0001), and the C allele (p<0.0001). The 50 bp Ins/Del polymorphism was associated with BC susceptibility for the Del allele (p=0.048), although the association between the dominant model AC/CC (rs2234694) and BC patients was evident for menopause [adjusted odds ratio (OR) 1.65 (95% CI 1.05-2.7); p=0.048], Ki-67 (>= 15%) (OR1.9, 95% CI 1.14-3.16, p=0.016), and the presence of DM2 (OR 2.4, 95% CI 1.35-4.31, p=0.003). A protective association for BC of the rs2234694 polymorphism was observed in patients younger than 50 years positive for estrogen receptor (ER) and progesterone receptor (PR), carrying the AC genotypes (OR 0.47, 95% CI 0.23-0.94, p= 0.033) and CC (OR 0.11, 95% CI 0.013-1.07, p=0.047). The association between the InsDel/DelDel (dominant model; 50 bp Ins/Del) genotype and BC with metastatic lymph nodes (OR 1.5, 95% CI 1.1-2.25, p=0.019), hematologic toxicity (OR 1.5, 95%CI 1.1-2.23, p=0.015), gastric toxicity (OR 1.5, 95%CI 1.1-2.07, p=0.030), and Ki-67 (>= 15%) (OR1.6, 95%CI 1.2-2.26, p=0.002) was evident, indicating that these factors may contribute significantly to BC risk. The C/Ins haplotype was also associated with BC susceptibility (OR3.47, 95% CI 1.62-7.74, p=0.001). CONCLUSIONS: rs2234694 and 50 bp Ins/Del polymorphisms in the SOD1 gene were associated with BC susceptibility in a Mexican population. A protective association for BC of the rs2234694 polymorphism was observed in patients younger than 50 years positive for ER and PR, carrying the AC genotypes. The haplogenotypes AA/InsIns and AC/InsDel could contribute significantly to BC risk in gastric and hematologic toxicities, metastatic lymph nodes, and the presence of DM2 in the Mexican population analyzed.