In patients with breast cancer and fibroadenomas, the catalase activity statistically significantly decreased (p = 0.0001), but SOD (p = 0.0270) and GGT (p = 0.0000) activity increased, and the NO (p = 0.0000) and MDA (p = 0.0007) levels increased compared with the healthy control. The gene discussed is SOD1; the disease is Fibroadenoma.