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Radiofrequency Ablation Therapy for Large Benign Thyroid Nodules

      To the Editor: We read with great interest a report by Hamidi et al,

      Hamidi O, Callstrom MR, Lee RA, et al. Outcomes of radiofrequency ablation therapy for large benign thyroid nodules: a Mayo Clinic case series [published online ahead of print March 21, 2018]. Mayo Clin Proc. https://doi.org/10.1016/j.mayocp.2017.12.011.

      titled “Outcomes of Radiofrequency Ablation Therapy for Large Benign Thyroid Nodules: A Mayo Clinic Case Series.” Hamidi et al

      Hamidi O, Callstrom MR, Lee RA, et al. Outcomes of radiofrequency ablation therapy for large benign thyroid nodules: a Mayo Clinic case series [published online ahead of print March 21, 2018]. Mayo Clin Proc. https://doi.org/10.1016/j.mayocp.2017.12.011.

      presented a retrospective review of 14 patients with predominantly solid thyroid nodules (TNs) treated with radiofrequency ablation (RFA) at the Mayo Clinic. The authors achieved 44.6% of median volume reduction with 8.6 months of the median follow-up period. The clinical efficacy was proved by resolution of compressive symptoms and improvement of cosmetic concerns. There were minor complications (21%) and no reported major complications. They concluded that RFA has an acceptable safety profile and should be considered as a low-risk alternative to conventional treatment of symptomatic benign TNs.
      We congratulate the authors for their meaningful results. Perhaps most importantly, this is the first research reporting the experience of thyroid RFA from the United States. We are certain that this research will be meaningful for both physicians and patients within the United States.
      However, several factors should be considered in technical and clinical aspects to achieve sustainable results in the future. The research enrolled large-sized TNs (mean volume, 24 mL). These results were may be induced by using the standard RFA techniques, the transisthmic approach and the moving-shot technique, which are recommended by current RFA guidelines.
      • Na D.G.
      • Lee J.H.
      • Jung S.L.
      • et al.
      Korean Society of Thyroid Radiology (KSThR)Korean Society of Radiology
      Radiofrequency ablation of benign thyroid nodules and recurrent thyroid cancers: consensus statement and recommendations.
      In addition, the authors used general anesthesia. However, most of the previous RFA studies used local anesthesia in the perithyroidal area because sensory nerves are present in the perithyroidal area (not inside the thyroid gland).
      • Park H.S.
      • Baek J.H.
      • Choi Y.J.
      • Lee J.H.
      Innovative techniques for image-guided ablation of benign thyroid nodules: combined ethanol and radiofrequency ablation.
      Therefore, pain during RFA is tolerable in most patients only using perithyroidal lidocaine injection. Moreover, apart from the usual problems of general anesthesia, monitoring of voice changes by nerve damage during the RFA procedure is impossible under general anesthesia. If voice change is detected during ablation, immediate cessation of RFA and injection of cold dextrose 5% in water (D5W) may recover voice problems induced by thermal damage. Therefore, local anesthesia is a safer pain control method than general anesthesia. Although a large population multicenter study reported only 1% of voice-related complications during RFA of benign nodules,
      • Baek J.H.
      • Lee J.H.
      • Sung J.Y.
      • et al.
      Korean Society of Thyroid Radiology
      Complications encountered in the treatment of benign thyroid nodules with US-guided radiofrequency ablation: a multicenter study.
      a recent large population single-center study reported a higher incidence of nerve injury (including recurrent laryngeal nerve, spinal accessory nerve, and sympathetic ganglion) during treatment of recurrent thyroid cancers.
      • Kim C.
      • Lee J.H.
      • Choi Y.J.
      • Kim W.B.
      • Sung T.Y.
      • Baek J.H.
      Complications encountered in ultrasonography-guided radiofrequency ablation of benign thyroid nodules and recurrent thyroid cancers.
      Therefore, current RFA guidelines recommend local anesthesia.
      The authors stressed single-session RFA for benign TNs because they achieved acceptable results at 8-month follow-up. In addition, single-session RFA is cost-effective compared with the surgical procedure. However, we should consider the long-term results of thermal ablations (ie, radiofrequency or laser) for benign TNs. In long-term studies with single-session laser ablation (LA), there has been a tendency of marginal regrowth at 2- to 3-year follow-up. Døssing et al
      • Døssing H.
      • Bennedbæk F.N.
      • Hegedüs L.
      Long-term outcome following interstitial laser photocoagulation of benign cold thyroid nodules.
      reported that 35% patients (27 of 78 patients) had thyroid surgery because of an unsatisfactory result 67 months later following LA, mainly due to regrowth of the nodule. Valcavi et al
      • Valcavi R.
      • Riganti F.
      • Bertani A.
      • Formisano D.
      • Pacella C.M.
      Percutaneous laser ablation of cold benign thyroid nodules: a 3-year follow-up study in 122 patients.
      reported 9% (11 of 122 patients) recurrence rate at 3-year follow-up. Their volume reduction was maximum at 2 years but slightly decreased at 3 years. It is induced by regrowth of treated nodules. This phenomenon is commonly observed after single-session treatment by LA because tumor regrowth occurs gradually during a follow-up period after an initial improvement of the clinical symptoms. In the single-session study in Mayo Clinic, the authors reported a similar result. In Figure 2, volume reduction at 12 to 24 months was 54.3% but decreased to 52.8% at 24-month follow-up. This result suggests that marginal regrowth started during 12- to 24-month follow-up. In response to this phenomenon, Korean groups have proposed and performed a complete tumor ablation. Two Korean reports of long-term results showed continuous volume reduction over years.
      • Lim H.K.
      • Lee J.H.
      • Ha E.J.
      • Sung J.Y.
      • Kim J.K.
      • Baek J.H.
      Radiofrequency ablation of benign non-functioning thyroid nodules: 4-year follow-up results for 111 patients.
      • Jung S.L.
      • Baek J.H.
      • Lee J.H.
      • et al.
      Efficacy and safety of radiofrequency ablation for benign thyroid nodules: a prospective multicenter study.
      In a single-center study, Lim et al
      • Lim H.K.
      • Lee J.H.
      • Ha E.J.
      • Sung J.Y.
      • Kim J.K.
      • Baek J.H.
      Radiofrequency ablation of benign non-functioning thyroid nodules: 4-year follow-up results for 111 patients.
      reported 90% volume reduction at 1 year and 93.5% at 4 years. In a multicenter prospective study, Jung et al
      • Jung S.L.
      • Baek J.H.
      • Lee J.H.
      • et al.
      Efficacy and safety of radiofrequency ablation for benign thyroid nodules: a prospective multicenter study.
      also reported gradual volume reduction over years (80.3% at 1 year, 89.2% at 3 years, and 91.9% at 4 years).
      In conclusion, the Mayo Clinic study confirmed that ultrasound-guided RFA is a clinically effective and safe outpatient treatment in patients with symptomatic or steadily growing benign, large, predominantly solid TNs, reproducing the experience generated in European and Asian studies. However, we should consider the pain control method for safety and the treatment strategy to achieve reasonable long-term efficacy.

      References

      1. Hamidi O, Callstrom MR, Lee RA, et al. Outcomes of radiofrequency ablation therapy for large benign thyroid nodules: a Mayo Clinic case series [published online ahead of print March 21, 2018]. Mayo Clin Proc. https://doi.org/10.1016/j.mayocp.2017.12.011.

        • Na D.G.
        • Lee J.H.
        • Jung S.L.
        • et al.
        • Korean Society of Thyroid Radiology (KSThR)
        • Korean Society of Radiology
        Radiofrequency ablation of benign thyroid nodules and recurrent thyroid cancers: consensus statement and recommendations.
        Korean J Radiol. 2012; 13: 117-125
        • Park H.S.
        • Baek J.H.
        • Choi Y.J.
        • Lee J.H.
        Innovative techniques for image-guided ablation of benign thyroid nodules: combined ethanol and radiofrequency ablation.
        Korean J Radiol. 2017; 18: 461-469
        • Baek J.H.
        • Lee J.H.
        • Sung J.Y.
        • et al.
        • Korean Society of Thyroid Radiology
        Complications encountered in the treatment of benign thyroid nodules with US-guided radiofrequency ablation: a multicenter study.
        Radiology. 2012; 262: 335-342
        • Kim C.
        • Lee J.H.
        • Choi Y.J.
        • Kim W.B.
        • Sung T.Y.
        • Baek J.H.
        Complications encountered in ultrasonography-guided radiofrequency ablation of benign thyroid nodules and recurrent thyroid cancers.
        Eur Radiol. 2017; 27: 3128-3137
        • Døssing H.
        • Bennedbæk F.N.
        • Hegedüs L.
        Long-term outcome following interstitial laser photocoagulation of benign cold thyroid nodules.
        Eur J Endocrinol. 2011; 165: 123-128
        • Valcavi R.
        • Riganti F.
        • Bertani A.
        • Formisano D.
        • Pacella C.M.
        Percutaneous laser ablation of cold benign thyroid nodules: a 3-year follow-up study in 122 patients.
        Thyroid. 2010; 20: 1253-1261
        • Lim H.K.
        • Lee J.H.
        • Ha E.J.
        • Sung J.Y.
        • Kim J.K.
        • Baek J.H.
        Radiofrequency ablation of benign non-functioning thyroid nodules: 4-year follow-up results for 111 patients.
        Eur Radiol. 2013; 23: 1044-1049
        • Jung S.L.
        • Baek J.H.
        • Lee J.H.
        • et al.
        Efficacy and safety of radiofrequency ablation for benign thyroid nodules: a prospective multicenter study.
        Korean J Radiol. 2018; 19: 167-174

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