[Antioxidant barrier in patients with gastric cancer--preliminary study]

Gastric carcinoma is one of the most common malignancies of causes of cancer death world-wide, although its incidence and mortality and decreasing, particularly in developed countries. One of the many factors in its etiopathogenesis are free oxygen radicals and their derivatives, excess of which comes from disturbances of enzymatic and nonenzymatic mechanisms of antioxidant barrier. The aim of this study was the evaluation activities of antioxidant enzymes: superoxide dismutase (CuZnSOD, MnSOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione transferase (GST), glutathione reductase (GSH-R) as well as measurement of glutathione (GSH) and malondialdehyde (MDA) levels both in tissues (cancer and healthy) and in blood serum obtained from patients with gastric cancer.

MnSOD and glutathione dependent enzymes (GSH-Px, GST, GSH-R) activities in gastric cancer were found to be higher than those in healthy stomach tissues. In pre- and postoperative blood serum from patients with gastric cancer was observed increase of CAT and GST as well as decrease of CuZnSOD and GSH-Px compared with the blood serum from healthy blood donors (control group). In preoperative blood serum from patients with gastric cancer GSH-R activity was lower than in control serum, whereas in postoperative serum it was higher compared with serum of the control group. Reduced GSH level was found to be lower in gastric cancer than this in healthy stomach tissue, adjacent to the cancer. Its level was also lower in pre- and postoperative blood serum of patients with gastric cancer compared with level in control serum. MDA concentration was found to be much higher in gastric cancer than this in healthy stomach tissue, whereas weren't significant differences between level of MDA in pre- and postoperative blood serum.

Our results showed that functioning of antioxidant barrier of organism is severely impaired in patients with gastric cancer.