IMPAIRED ENZYMATIC ANTIOXIDANT DEFENSE-MECHANISM IN CANCEROUS HUMAN THYROID TISSUES

The activities of total superoxide dismutase (SOD), glutathione peroxi dase (GSH-Px) and catalase (CAT) enzymes were measured in cancerous an d non-cancerous adjacent tissues from 15 patients with follicular thyr oid cancer containing single nodule. SOD and GSH-Px activities were fo und lower but malondialdehyde levels higher in cancerous tissues compa red with those of noncancerous ones. However, no difference was found between CAT activities of the tissues. Activity decrease of GSH-Px enz yme in cancerous tissue was greater than that of SOD enzyme. Results s uggested that enzymatic free radical defense system was significantly impaired and lipid peroxidation increased in the cancerous human thyro id tissues.