ABSTRACT
Blood selenium and zinc levels and selenium-dependent glutathione peroxidase activity [GSH-Px] in 22 patients with untreated cancer of the oral cavity were studied before and after the surgical removal of the mass. In addition, GSH-Px activity in tumor and normal tissues were determined. Normal blood from 10 cancer-free and age-matched patients served as controls. Mean plasma selenium and zinc levels and GSH-Px activity were significantly depressed in both pre-and post-operative cancer patients when compared to controls. On the other hand, mean plasma selenium and zinc levels and GSH-Px activity of the post-operative patients were not changed significantly when compared to the corresponding levels of the pre-operative ones. Moreover, the mean GSH-Px activity for malignant tissues was significantly lower than the corresponding activity in either the benign or the adjacent normal tissues. No significant difference was found in the activity of GSH-Px between benign and normal tissues. Significant positive correlations were found between plasma GSH-Px and selenium [r 0.909] and between selenium and zinc levels [r 0.883] in the pre-operative cancer patient group. The results suggest that selenium, zinc and GSH-Px are involved in malignant neoplasia of the oral cancer