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.