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Background/Objectives: This study investigated the association between the rs13306703 and rs8192288 variants of the superoxide dismutase 3 (SOD3) gene and breast cancer (BC) in the Mexican population, conducting both genetic and in silico analyses. Methods: 357 healthy women and 386 BC patients were studied using TaqMan assays, qPCR, and RFLP-PCR. Results: The TT genotype and a recessive pattern of these variants were risk factors for BC (p < 0.05). Specifically, the TT genotype of rs13306703 was associated with metastatic lymph nodes, tumor progression (III–IV), luminal A, nonresponse to chemotherapy, and ki-67 ≥ 20% with diabetes mellitus (DM). Meanwhile, the GT genotype of rs8192288 was associated with menopause, luminal A, tumor progression (III–IV), ki-67 ≥ 20%, and a positive estrogen receptor with nonresponse to chemotherapy. Additionally, the TT genotype combined with DM was identified as a BC risk factor (p < 0.05). The TT haplotype was also found to be a risk factor for BC. In silico analysis suggested that these variants might influence SOD3 regulation by affecting transcription factors and active enhancer sites. Conclusions: The rs13306703 and rs8192288 variants of the SOD3 gene were associated with an increased risk of BC and may alter SOD3 regulation through effects on transcription factors, active enhancers, and transcription start sites, with modified motifs in breast epithelium cells.

The superoxide dismutase (SOD) is the principal antioxidant defense system in the body that is activated by a reactive oxygen species. Some variants of the SOD2 gene have been associated with cancer. The rs4880 variant was determined by PCR real-time and the rs5746136 variant by PCR-RFLP in healthy subjects and in breast cancer (BC) patients. The rs4880 and rs5746136 variants were associated with BC susceptibility when BC patients and the control group were compared for the CT, TT, CTCC, and the T alleles (p < 0.05). The CT genotype of the rs4880 variant showed significant statistical differences in patients and controls aged ≤ 45 years old, and with hormonal consumption (p < 0.05). The rs4880 variant was associated with BC patients with CTTT genotype and obesity, the presence of DM2-SAH, and a non-chemotherapy response (p < 0.05). Additionally, the rs5746136 variant was associated with susceptibility to BC with Ki-67 (≥20%), luminal A type BC, and a chemotherapy partial response (p < 0.05) in BC patients who carry TT, TC, and CTTT genotypes, respectively. The haplotype T/T (OR 1.98; 95% CI 1.20–3.26, p = 0.005) was observed to be a risk factor for BC. The rs4880 and rs5746136 variants in the SOD2 gene were associated with BC susceptibility.