A multi-institutional analysis of outcomes following stereotactic body radiation therapy for management of metastases from squamous cell carcinomas of the head and neck.

Background: There is limited data on clinical outcomes following SBRT for patients with metastatic head and neck squamous cell carcinoma (mHNC).

Method: An international SBRT registry was utilized to identify patients. LC and OS were evaluated with the Kaplan-Meier method and a Cox-proportional hazards model for multivariate analysis (MVA) to assess potential prognostic factors.

Results: We identified 81 patients with 98 lesions treated with SBRT. Areas treated included the lung (53.0%), non-regional lymph nodes (16.0%), and spine (12.3%). OS rates at 1 year and 2 years were 66.4% and 43.1%, respectively. Utilizing KPS, spinal disease, and GTV, 1-year OS estimates were 90.9%, 70.4%, 54.5%, and 25% for patients with 0-3 of these factors, respectively (p = 0.002). One-year and 2-year LC rates were both 93.3%. Roughly 17% of patients reported toxicities (none Grade 3+).

Conclusions: SBRT resulted in promising LC for mHNC patients. Spinal disease, GTV, and KPS should be considered in selecting patients with mHNC that may benefit from SBRT.