Preliminary Report Examining Efficacy and Safety of Radiofrequency Ablation for the Treatment of Skin-Involving Recurrent Thyroid Cancer.

Background: This study assessed the efficacy and safety of ultrasound (US)-guided radiofrequency ablation (RFA) for treatment of skin-involving recurrent thyroid cancer. Methods: In this retrospective case series study, 43 patients (mean age: 67.9 ± 14.4 years; 31 females) with skin-involving recurrent thyroid cancer were treated with RFA for a total of 50 tumors between May 2008 and March 2023. The location of the tumor was classified into epidermis, dermis, or hypodermis on the basis of the involved skin layer. After RFA, the technique efficacy (absence of detectable vasculature and volume reduction at 12 months), clinical success (resolution of symptoms or cosmetic problems), volume reduction ratio (VRR), complete disappearance of tumor, and complications were assessed. Results: Of the 50 recurrent tumors, 9 involved the epidermis, 10 involved the dermis, and 31 involved the hypodermis. A total of 88 RFA sessions (mean, 1.8; range: 1-6) were performed. The technique efficacy at 1 year was 72% (36/50 [confidence interval or CI: 59.6-84.4%]). At the last follow-up (median [interquartile range]: 2.7 [1.1-4.5] years), the clinical success rate was 86% (44/50), the complete disappearance rate 54% (27/50), and the mean VRR 77.3% ± 44.2%. In a subgroup analysis comparing epidermis/dermis vs. hypodermis, there was no statistical difference in technique efficacy (57.9% [11/19] vs. 80.6% [25/31], p = 0.085), clinical success rate (78.9% [15/19] vs. 90.3% [28/31], p = 0.265), complete disappearance rate (42.1% [8/19] vs. 51.6% [16/31], p = 0.541), or mean VRR (65.5% vs. 84.6%, p = 0.141). Skin burns were observed in 4.9% per treatment session (2/41 [CI: 0-11.3%]) of epidermis/dermis-involving tumor procedures and none of the hypodermal tumor procedures. No patients experienced life-threatening or major complications. Conclusions: RFA might serve as a promising approach for managing skin-involving recurrent thyroid cancer, with no major complications reported in this preliminary study. Recurrent tumors involving the epidermis/dermis may pose a higher risk of skin burns than tumors involving the hypodermis. Early intervention with RFA before the tumor extends to the epidermis/dermis may thus be preferable.