Evaluation of saliva glutathione, glutathione peroxidase, and malondialdehyde levels in head-neck radiotherapy patients

Background/aim: It is believed that radiotherapy has important effects on oxidant/antioxidant systems. Oxidative stress occurs when the balance between oxidant formation and antioxidant defense is disrupted in favor of oxidants. The aim of this study was to determine the biochemical changes in saliva pre- and postradiotherapy in head-neck radiotherapy patients and to find out the effects of radiation on glutathione (GSH), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) levels in saliva. Materials and methods: This study included 16 patients undergoing head-neck radiotherapy in Atatürk University Research Hospital. The levels of GSH, GSH-Px, and MDA were measured in saliva samples taken from the patients pre- and postradiotherapy. The same biochemical parameters were also measured in saliva samples from 30 healthy individuals who did not undergo head-neck radiotherapy. The data obtained were analyzed using the paired t-test and the Mann–Whitney U test. Results: When the levels of GSH (P > 0.05), GSH-Px (P > 0.05), and MDA (P < 0.05) in saliva were compared pre- and postradiotherapy in the patient group, the only significant increase was detected in the MDA level postradiotherapy. When the pre- and postradiotherapy levels of saliva GSH (P < 0.01, P < 0.001, respectively), GSH-Px (P > 0.05, P < 0.05, respectively), and MDA (P < 0.01, P < 0.001, respectively) were compared with those of the control group, it was revealed that the GSH level was significantly lower and the MDA level was significantly higher in both pre- and postradiotherapy compared to the control group. Also, only the postradiotherapy saliva GSH-Px level was found to be significantly lower than the control group. Conclusion: These findings show that the changes in saliva GSH, GSH-Px, and MDA levels in patients with head-neck malignity intensified due to radiation.