Role of Repeated Radiofrequency Ablation for Patients with Lung Metastases of Head and Neck Adenoid Cystic Carcinoma: Long-term Single-center Study in 16 Patients with 289 Tumors

<b>Purpose:</b> To retrospectively assess the clinical outcomes of repeated radiofrequency ablation for lung metastases of head and neck adenoid cystic carcinoma. <b>Material and Methods:</b> Consecutive 16 patients (mean age, 55.3 years) who were treated with radiofrequency ablation for 289 lung metastases were included. A 17-gauge electrode was used in all radiofrequency ablation procedures and placed under computed tomography fluoroscopic guidance. Evaluated were safety, technical success, local tumor control, and survival. <b>Results:</b> In total, 143 radiofrequency ablation sessions were performed for 289 lung metastases. One session of radiofrequency ablation was not completed due to pleural hemorrhage during the procedure, resulting in a technical success rate of 99.3% (142/143). Major complications (pneumothorax and hemorrhage) occurred in 40 sessions (27.9%, 40/143). During the mean follow-up period of 5.5 ± 3.6 years (range, 0.4-13.4 years), local tumor progression was observed in 16 tumors (5.5%, 16/289) and repeated radiofrequency ablation (93.8%, 15/16) or metastasectomy (6.2%, 1/16) was performed for all locally progressed lung metastases. The local tumor control rates were 97.1% (95% confidence interval, 95.1%-99.2%) and 89.5% (95% confidence interval, 84.0%-95.0%) at 1- and 5-year. Median survival time after initial lung radiofrequency ablation was 9.8 years and 1-, 3-, 5-, and 10-year overall survival rates were 100% (95% confidence interval, 100%), 91.7% (95% confidence interval, 76.0%-100%), 64.3% (95% confidence interval, 35.7%-92.9%), and 35.7% (95% confidence interval, 0%-70.8%), respectively. <b>Conclusions:</b> Repeated radiofrequency ablation for multiple lung metastases of adenoid cystic carcinoma was feasible and safe and may allow survival with good local control of lung metastases.