Salivary parameters as predictive markers for radiation-induced treatment response in head and neck cancers: An investigational study

Background: This study evaluates the predictive significance of salivary amylase, glutathione, lipid peroxides, and lactate dehydrogenase in the treatment of head and neck cancer patients who undergo curative radiotherapy/chemoradiotherapy. Methods: The volunteers for the study included head and neck cancer patients that required curative radiotherapy/chemoradiotherapy. Patients provided saliva and blood samples before the start of radiation treatment and 24 hours after the first radiation fraction of 2 Gy (before the start of the second fraction). Samples were assessed for the levels of blood and salivary amylase, glutathione, lipid peroxides, and lactate dehydrogenase by standard laboratory methods. Clinical tumor radioresponse was assessed one month after the completion of treatment as complete responders, partial responders, and nonresponders. Results: The results indicated a significant increase in the levels of amylase, lactate dehydrogenase, and lipid peroxides; and a concomitant decrease in the levels of glutathione P<0.05 - P<0.0001 in saliva and blood. The correlation between the differences in each biochemical parameter with that of the treatment response showed a significant correlation only for the salivary lactate dehydrogenase (R2=0.25; P<0.02). Conclusion: The results indicate that salivary lactate dehydrogenase can be a useful predictive marker to ascertain radiation-induced tumor regression in head and neck cancers.