Stereotactic Body Radiotherapy for Metastases to the Head and Neck

Abstract

<h3>Purpose/Objective(s)</h3> To report clinical outcomes for patients with metastatic disease to the head and neck (HN) treated with stereotactic body radiation therapy (SBRT) at a large academic center. <h3>Materials/Methods</h3> A retrospective review of SBRT patients treated to the HN from 2012 to 2020 was conducted. Treatment indications included: oligometastases, oligoprogression, and local control of a dominant area of progression (DAP). Kaplan-Meier method was used to estimate local control (LC), regional control (RC), overall survival (OS), and progression-free survival (PFS). Univariable (UVA) and multivariable analyses (MVA) were performed to determine the relationship between clinical characteristics and outcomes. Grade 3—4 acute and late toxicities were reported by the Common Terminology Criteria for Adverse Events v5.0. <h3>Results</h3> Fifty-six patients (58 lesions) were analyzed with a median follow-up of 16 months. Primary cancer sites included lung (25%), kidney (19.6%), breast (19.6%) and other (35.8%). SBRT indications were: oligometastases (n = 24, 42.9%), oligoprogression (n = 11, 19.6%), and local control of a DAP (n = 21, 37.5%). Most patients received SBRT to a single neck node (n = 48, 82.8%). Median SBRT dose was 40 Gy (range: 25-50 Gy) in 5 fractions, with a median biologically effective dose (BED₁₀) of 72 Gy (range: 37.5-100 Gy). One- and 2-year LC rates were 97.6% and 72.7%. One- and 2-year RC rates were 100% and 86.7%, respectively. Median OS was 19.2 months (95% confidence interval [CI], 14.8-69.4) and median PFS was 7.4 months (95% CI, 5.2-11.9). The 1-year OS and PFS rates for oligometastases, oligoprogression and DAP were 95.8%, 63.6% and 38.1% (p = 0.0039), and 56.5%, 27.3% and 19.1% (p = 0.0004), respectively. On MVA, treatment indication and histology were found to be predictive for OS and treatment indication and prior systemic therapy were the predictive factors for PFS. Ten patients (18%) developed acute grade ≥ 3 treatment-related toxicity and six patients (11%) experienced late grade ≥ 3 toxicity. <h3>Conclusion</h3> The use of SBRT for metastatic disease to the HN provided excellent LC rates with low rates of regional failure. Patients with oligometastatic disease had better OS and PFS than others. This treatment resulted in an acceptable toxicity profile.