The changes in irradiated salivary gland function of patients with head and neck tumors treated with radiotherapy

To investigate and analyze changes in irradiated salivary gland function of patients with head and neck tumors treated with radiotherapy. Thirty-seven patients with head and neck tumors, who received 40-70 Gy of irradiation to all major salivary glands, were analyzed. The weights of saliva secreted for 10 minutes at rest, and for 5 minutes with vitamin C stimulation, were measured. The salivary gland function was defined by the weight of saliva. With vitamin C stimulation, the weight of saliva in patients whose doses were ≤50 Gy, was significantly higher than that of patients whose doses were ≥58 Gy (2.48±0.33 g vs. 0.73±0.18 g, P=0.0003). When doses administered to salivary glands were ≤50 Gy, the stimulated saliva secretion recovered over time, after irradiation. However, when the doses of irradiation were ≥58 Gy, there was no recovery in saliva secretion even after a few years. Multiple regression analysis showed that age and chemotherapy may not affect salivary gland function even years after radiotherapy. When salivary glands were irradiated with doses ≤50 Gy, gradual recovery of salivary gland function was observed over time, whereas there was no significant recovery when the irradiation dose was >58 Gy. (author)