Biochemical analysis of saliva in head and neck cancer patients receiving definitive chemoradiotherapy

Background: Radiation therapy leads to salivary gland damage that causes xerostomia, the standard radiation-induced complication during radiotherapy that affects the quality of life in head and neck cancer patients. This study was conducted at a tertiary cancer institute in Punjab state to analyze the influence of radiation therapy on various parameters and substances of saliva. Materials and Methods: Sixty head and neck cancer patients who underwent conventional radiotherapy on a Cobalt machine were included. Saliva was collected in both stimulated and unstimulated states. Stimulated whole saliva was collected by applying two to three drops of citric acid solution (2%) over the dorsum of the tongue bilaterally at 30-s intervals for 2 min. Biochemical changes in the whole saliva were evaluated by biochemical methods at baseline, completion of therapy, and 3 and 6 months post-radiotherapy completion. Results: The lowest concentration of proteins was seen after the therapy in unstimulated and stimulated saliva. Salivary protein levels showed a rising trend toward baseline in 3- and 6-month posttherapy samples. The peak value (0.4 mg/dl) was reached in the stimulated saliva after therapy. Salivary amylase did not show a consistent concentration graph. The salivary concentrations of sodium, potassium, and chloride showed peak values after radiotherapy. The lowest salivary pH was obtained at completion of therapy, both in unstimulated and stimulated saliva. After 3 months of chemoradiotherapy, the saliva reached a pH value of 8.3, whereas 6-month posttherapy sample showed a pH value of 8.4 in both unstimulated and stimulated saliva. Conclusions: At the completion of chemoradiotherapy, the total salivary protein, albumin, and inorganic components (calcium, magnesium, phosphorus) showed a downward trend from the baseline values due to the damage caused to the acinar part of the salivary gland by radiotherapy. The rise in salivary electrolytes' concentrations is attributed to the fact that even though there is loss of absorptive property of the tubular portion of the salivary gland, it retains its secretory property. Saliva becomes thick, scarce, tenacious, and acidic during the period of chemoradiotherapy.