Parotid gland function during and following radiotherapy of malignancies in the head and neck : a consecutive study of salivary flow and patient discomfort

Radiotherapy of tumours in the head and neck region usually involves the salivary glands in the treatment volume with ensuing dryness and discomfort. In the present study, a prospective evaluation of the same patients were performed before, during radiotherapy and 6, 12 and 18 months after the end of treatment. Three different groups were outlined, one receiving doses not exceeding 45 Gy, another 47-52 Gy and a third group treated with doses over 64 Gy. All but one of the patients receiving doses less than 52 Gy showed a recovery of secretion beginning after 2 months with a continuous improvement of the salivary flow up to 18 months. Doses exceeding 64 Gy caused irreversibly depressed parotid function in the vast majority of glands. The subjective experience of discomfort with dry mouth was not at all correlated to the initial flow rate. Treatment with unilateral technique and doses below 52 Gy caused just no or slight dryness and 3 out of 4 patients with bilateral involvement of the glands displayed problem with subjective dryness even after 18 months. Doses over 64 Gy with one gland involved had only slight dryness, however, patients with both glands affected showed severe problems with dryness. It has to be emphasised that there were relatively large interindividual differences with respect to salivary flow and discomfort of dryness. It is obvious that these patients need a careful dose planning and a close follow up with co-operation between radiotherapeutists and dentists.