Patients with high risk salivary gland
malignancies are at increased risk of local failure. We present our institutional experience with dose escalation using hypofractionated stereotactic body radiotherapy (SBRT) in a subset of this
rare disease. Over the course of 9 years, 10 patients presenting with skull base invasion, gross disease with one or more adverse features, or those treated with adjuvant radiation with three or more pathologic features were treated with intensity-modulated
radiation therapy followed by hypofractionated SBRT boost. Patients presented with variable
tumor histologies, and in all but one, the
tumors were classified as poorly differentiated high grade. Four patients had gross disease, three had gross residual disease, three had skull base invasion, and two patients had rapidly recurrent disease (≤6 months) that had been previously treated with surgical resection. The median stereotactic radiosurgery boost dose was 17.5 Gy (range 10-30 Gy) given in a median of five fractions (range 3-6 fractions) for a total median cumulative dose of 81.2 Gy (range 73.2-95.6 Gy). The majority of the patients received
platinum based concurrent
chemotherapy with their radiation. At a median follow-up of 32 months (range 12-120) for all patients and 43 months for surviving patients (range 12-120), actuarial 3-year locoregional control, distant control, progression-free survival, and overall survival were 88, 81, 68, and 79%, respectively. Only one patient failed locally and two failed distantly. Serious late toxicity included graft ulceration in one patient and
osteoradionecrosis in another patient, both of which underwent surgical reconstruction. Six patients developed
fibrosis. In a subset of patients with salivary gland
malignancies with skull base invasion, gross disease, or those treated adjuvantly with three or more adverse pathologic features, hypofractionated SBRT boost to
intensity-modulated radiotherapy yields good local control rates and acceptable toxicity.