SOD1 and gastric cancer: The study of superoxide dismutase activity revealed an increase in this indicator in the groups of patients at stages I and II compared to the control (SOD: p1–2 < 0.001; p1–3 < 0.001) and a decrease in the activity of this enzyme in patients with gastric cancer at stages III and IV compared to the control and with the groups of patients at stages I and II (p1–4 = 0.03; p1–5 < 0.001).