Locoregional Control of Metastatic Well-Differentiated Thyroid Cancer by Ultrasound-Guided Radiofrequency Ablation

OBJECTIVE. The purpose of this study was to evaluate the efficacy and safety of ultrasound-guided radiofrequency ablation (RFA) in the control of metastatic well-differentiated thyroid carcinoma in patients for whom surgery is not feasible. MATERIALS AND METHODS. Between December 2004 and June 2008, 12 metastatic differentiated thyroid carcinomas (mean diameter, 13.8 mm; range, 4-28 mm) in 10 patients (six women, four men; mean age, 44.8 years) were treated with RFA. The inclusion criteria for RFA were fewer than three metastatic tumors confirmed with ultrasound-guided fine-needle aspiration biopsy, no metastatic tumor beyond the neck at RFA, and infeasibility of surgery. A radiofrequency generator and 18-gauge internally cooled electrodes with a 7-cm shaft length and 0.5- and 1-cm active tips were used depending on the size of the targeted tumors. Ten of the 12 metastatic tumors (83%) were treated in a single session of RFA, and the other two required two sessions. The ablation time ranged from 60 to 900 seconds. RESULTS. After treatment, the mean largest diameter decreased significantly from 13.8 +/- 7.0 mm to 3.3 +/- 3.9 mm (p = 0.002), as did mean volume, from 55.5 +/- 50.3 mm(3) to 5.7 +/- 9.3 mm(3) (p = 0.002). At the last follow-up evaluation, the serum thyroglobulin concentration had decreased in 7 of 10 patients. One patient had dysphonia immediately after RFA of a left surgical bed. CONCLUSION. Although surgery is the standard treatment of locally metastatic thyroid cancer, RFA is effective for locoregional control of metastatic well-differentiated thyroid carcinoma in patients for whom surgery is infeasible.