Outcomes and toxicities following stereotactic ablative radiotherapy for pulmonary metastases in patients with primary head and neck cancer

Background Metastatic head and neck cancers (HNCs) predominantly affect the lungs and have a two-year overall survival (OS) of 15% to 50%, if amenable for pulmonary metastasectomy. Methods Retrospective review of the two-year local control (LC), local-regional control (LRC) within the same lobe, OS, and toxicity rates in consecutive patients with metastatic pulmonary HNC who underwent stereotactic ablative radiotherapy (SABR) January 2007 to May 2018. Results Evaluated 82 patients with 107 lung lesions, most commonly squamous cell carcinoma (SCC; 64%). Median follow-up was 20 months (range: 9.0-97.6). Systemic therapy administered in 34%. LC, LRC, and OS rates were 94%, 90%, and 62%. Patients with oligometastatic disease had a higher OS than polymetastatic disease, 72% vs 44% (HR = 0.30, 95% CI: 0.14-0.64;P= .008). OS in oligometastatic non-SCC and SCC were 100% and 66% (P= .03). There were no grade >= 3 toxicities. Conclusions Metastatic pulmonary HNCs after SABR have a two-year OS rate comparable to pulmonary metastasectomy.