Gastric mucosal antioxidant activity in patients at increased risk of gastric cancer.

In 68 subjects the activities of Cu/Zn-superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were investigated in gastric mucosa. The patients were classified according to the histological finding into following groups: 12 with normal finding (N), 16 with superficial gastritis (SG), 13 with mild atrophic gastritis (MAG), 19 with severe atrophic gastritis (SAG) and 8 with gastritis after partial gastrectomy (PGG). The comparison of groups SG, MAG, SAG and PGG with the group N revealed the following changes: in SG increased SOD and GSH-Px, in MAG and SAG no significant changes, and in PGG increase in SOD, CAT and GSH-Px were observed. It was supposed that increased enzymatic activities were caused by higher concentration of active oxygen species produced by phagocytizing leukocytes in inflamed gastric mucosa. Administration of vitamin E resulted in significant reduction of SOD and CAT activities, on the other hand GSH-Px activity significantly increased. The explanation of this effect of vitamin E requires further studies. A prolonged interaction of active oxygen species with chemical carcinogens (N-nitroso- or diazonium compounds, PAH) can exhibit a significant promoting effect on the development of intestinal type of gastric cancer from its precancerous conditions, above all after partial gastrectomy.