Radiofrequency ablation to treat loco-regional recurrence of well-differentiated thyroid carcinoma

Abstract

Objective: To evaluate the efficacy of radiofrequency ablation (RFA) in the treatment of loco-regional, recurrent, and well-differentiated thyroid carcinoma.

Materials and methods: Thirty-five recurrent well-differentiated thyroid carcinomas (RTC) in 32 patients were treated with RFA, between March 2008 and October 2011. RTCs were detected by regular follow-up ultrasound and confirmed by biopsy. All patients had fewer than 3 RTCs in the neck and were at high surgical risk or refused to undergo repeated surgery. Average number of RFA sessions were 1.3 (range 1-3). Post-RFA biopsy and ultrasound were performed. The mean follow-up period was 30 months. Pre- and post-RFA serum thyroglobulin values were evaluated.

Results: Thirty-one patients with 33 RTCs were treated with RFA only, whereas 1 patient with 2 RTCs was treated with RFA followed by surgery. At the last follow-up ultrasound, 31 (94%) of the 33 RTCs treated with RFA alone completely disappeared and the remaining 2 (6%) RTCs showed decreased volume. The largest diameter and volume of the 33 RTCs were markedly decreased by 93.2% (from 8.1 ± 3.4 mm to 0.6 ± 1.8 mm, p < 0.001) and 96.4% (from 173.9 ± 198.7 mm(3) to 6.2 ± 27.9 mm(3), p < 0.001), respectively. Twenty of the 21 RTCs evaluated with post-RFA biopsies (95%) were negative for malignancy. One (5%) showed remaining tumor that was removed surgically. The serum thyroglobulin was decreased in 19 of 26 patients (73%). Voice change developed immediately after RFA in 6 patients (19%) and was spontaneously recovered in 5 patients (83%).

Conclusion: Radiofrequency ablation can be effective in treating loco-regional, recurrent, and well-differentiated thyroid carcinoma in patients at high surgical risk.

Keywords: Efficacy; Radiofrequency ablation; Recurrent thyroid cancer; Thyroid; Ultrasound.

Fig. 1

Three procedures to prevent major organ injuries near tumors in level 6. Metastatic tumor is detected in right level 6 on ultrasound (A, straight arrows). First, lidocaine is injected around tumor to separate invisible recurrent laryngeal nerve, trachea, and carotid artery from tumor and to provide pain control before ablation (B, arrowheads). Second, tumor is pulled away from three organs by tilting electrode during ablation (C, D, curved arrows). Third, cold fluid is injected around ablated tumor after ablation (E, arrowheads).

Fig. 2

Three procedures to prevent major organ injuries near tumor in level 3. Metastatic tumor (arrowhead) in right level 3 is detected near vagus nerve (straight arrow), common carotid artery (CCA) and internal jugular vein (IJV) on ultrasound (A). First, lidocaine is injected around tumor to separate visible vagus nerve (short arrow), CCA, IJV, and sternocleidomastoid muscle from tumor and to provide pain control before ablation (B, C, arrowheads). Second, tumor is pulled away from three major organs by tilting electrode during ablation (D, curved arrow). Third, cold fluid is injected around ablated tumor after ablation (not shown).

Fig. 3

39-year-old man with recurrent thyroid cancer in right level 3. Initial CT (A) and ultrasound (B) demonstrate recurrent nodule in right level 3 (arrows, 13 mm). One session of radiofrequency ablation (RFA) (1.0-cm electrode, 10-20 W, one minutes 20 seconds) is performed. Nodule shows decreased size with 76.9% volume reduction rate on post-RFA one-month follow-up ultrasound (not shown) and is invisible on 19-month follow-up ultrasound (C, arrows) and 22-month follow-up CT (D, arrows).

Fig. 4

38-year-old woman with recurrent thyroid cancer in right level 6. Initial CT (A) and ultrasound (B) show enhancing nodule in right level 6 (arrows, 18 mm). There is no enhancing nodule (arrows) on 2-month follow-up CT after radiofrequency ablation (RFA) (C). On ultrasound for post-RFA fine-needle aspiration (D), volume of this nodule was markedly reduced (87.0% volume reduction rate) and biopsy result was negative for malignancy.

Fig. 5

85-year-old woman with two recurrent thyroid cancers in right level 4 (23 mm and 26 mm). Recurrent node (23 mm) is seen on initial CT (A, arrows). Volume of this node is reduced, but it is still enhanced on CT scan after 1st radiofrequency ablation (RFA) (B, arrows). Suspicion of malignancy was demonstrated in this nodule on post-1st RFA biopsy. This nodule was surgically treated (C, arrows). Another recurrent node (26 mm) was completely treated with RFA (not shown).