IMRT with Stereotactic Body Radiotherapy Boost for High Risk Malignant Salivary Gland Malignancies: A Case Series

Abstract

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.

Stereotactic radiotherapy as planned boost after definitive radiotherapy for head and neck cancers: Systematic review

“…PFS rates were 80%–98% at 1 year, 70%–90% at 2 years, and 70%–90% at 3 years. LRFS was reported in four studies as follows: 91% at 1 year, 22 96% at 2 years, 22 82% at 3 years 18 85% in 4 years, 27 and 84% at 5 years 18 5.…”

“…The countries represented in this study were Korea ( n = 1), Japan ( n = 1), China ( n = 1), Taiwan ( n = 1), India ( n = 1), Mexico ( n = 1), United States ( n = 2), and Netherlands ( n = 1) 18–26 . Overall, studies ranged from the years 2006–2020, with a median follow‐up time range from 8–56 months.…”

The evolving landscape of salivary gland tumors

“…In addition, hypofractionated (high dose‐per‐fraction) techniques, such as stereotactic body RT, may be considered in the definitive setting either alone or as a boost after a lower dose of conventionally fractionated RT. Although small retrospective series suggest oncologic outcomes at least comparable to those of conventionally fractionated RT, there are no prospective data to support the use of stereotactic body RT in salivary gland malignancies 68,69 …”

“…Although small retrospective series suggest oncologic outcomes at least comparable to those of conventionally fractionated RT, there are no prospective data to support the use of stereotactic body RT in salivary gland malignancies. 68,69 SYSTEMIC THERAPY…”

Canine salivary gland carcinoma treated with stereotactic body radiation therapy: a retrospective case series

“…The majority (88.8%) of neoplasms described are of epithelial origin (3). There is sparse information regarding Gualtieri et al 10.3389/fvets. 2023.1202265 Frontiers in Veterinary Science 02 frontiersin.org clinical characteristics, treatment management, and outcome for dogs with salivary gland tumors (4).…”