Parotid saliva composition during and after irradiation of head and neck cancer.

Parotid saliva composition was studied before, during and up to 18 months after the irradiation period in 16 cancer patients treated for malignancies in the head and neck region. Stimulated parotid saliva was collected prior to radiotherapy and, when possible, weekly during treatment. New samples were taken 2, 4, 6, 12 and 18 months after the end of radiotherapy. Nine of the 16 patients were treated with bilateral irradiation fields and 7 patients with unilateral irradiation fields, with a total dose not exceeding 52 Gy. During the entire irradiation period the fraction of glands producing measurable volumes of saliva decreased to 40%. In the postirradiation period the number of active glands gradually increased and saliva secretion rate returned to an average of 72% of the initial value 18 months after the end of irradiation. The concentrations of the measured variables increased already during the first week of radiotherapy and at the end of the treatment period the concentrations for total protein, salivary peroxidase, hexosamine and salivary IgA were significantly increased. The concentrations for total protein, salivary peroxidase and salivary IgA were still increased 6 months after the end of irradiation. At the 18-months observation all concentrations had returned to normal, as evaluated in a paired t-test. The majority of glands irradiated with 40-52 Gy recovered not only in secretion rates but also with respect to the components studied in this investigation.