Post-operative treatment of malignant salivary gland tumours of the palate with iodine-125 brachytherapy.

Background And Purpose: Malignant minor salivary gland tumours are usually small and clinically indistinguishable from benign lesions. Surgery is the treatment of choice with post-operative radiotherapy for involved margins or unfavourable histology. We assessed the results of a series of such patients treated with iodine-125 brachytherapy in the form of a temporary applicator or implant.

Patients And Methods: There were nine patients with T1/T2 tumours of the hard and/or soft palate that had been excised. All had close or involved margins. Six were treated with a dental applicator alone, two with an applicator and additional I-125 seeds in tubes and one with an implant alone. The applicator consists of two layers of plastic made from a dental impression enclosing a predetermined number of I-125 seeds, 9-39, glued to one surface and a layer of ash metal to protect the tongue. It was inserted 1-3 months post-operatively and delivered 35-62 Gy, median 56 Gy, at 5-7 mm depth over 58-156 h, median 120 h, at 0.26-0.67 Gy/h, median 0.45 Gy/h.

Results: The patients have been followed up for 32-158 months, median 50 months, and there were no recurrences. The applicator was well tolerated. A confluent mucositis developed which lasted 3-4 weeks. One patient developed a mucosal ulcer which healed spontaneously.

Conclusions: Brachytherapy is an effective way of delivering post-operative radiotherapy to the hard and soft palate in patients with malignant salivary gland tumours that have been incompletely excised or have unfavourable histology. Local control is excellent, treatment time is short and morbidity is minimal.