Large Benign Thyroid Nodules 101: Ablation vs Surgery

Large Benign Thyroid Nodules 101: Ablation vs Surgery

Large Benign Thyroid Nodules 101: Ablation vs Surgery

To the Editor: We read with great interest a report by Hamidi et al,1 titled “Outcomes of Radiofrequency Ablation Therapy for Large Benign Thyroid Nodules: A Mayo Clinic Case Series.” Hamidi et al1 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.

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 al6 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 al7 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.8, 9 In a single-center study, Lim et al8 reported 90% volume reduction at 1 year and 93.5% at 4 years. In a multicenter prospective study, Jung et al9 also reported gradual volume reduction over years (80.3% at 1 year, 89.2% at 3 years, and 91.9% at 4 years).

. 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.
  2. Na, D.G., Lee, J.H., Jung, S.L…., Korean Society of Thyroid Radiology (KSThR), and Korean Society of Radiology. Radiofrequency ablation of benign thyroid nodules and recurrent thyroid cancers: consensus statement and 
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