Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Radiofrequency ablation (RFA) is a minimally invasive treatment modality used as an alternative to surgery in patients with benign thyroid nodules, recurrent thyroid cancers (RTCs), and primary thyroid microcarcinomas. The Korean Society of Thyroid Radiology (KSThR) initially developed recommendations for the optimal use of RFA for thyroid tumors in 2009 and revised them in 2012 and 2017. As new meaningful evidence has accumulated since 2017 and in response to a growing global interest in the use of RFA for treating malignant thyroid lesions, the task force committee members of the KSThR decided to update the guidelines on the use of RFA for the management of RTCs based on a comprehensive analysis of current literature and expert consensus.

Objective: This study investigates the long-term efficacy and safety of ultrasound (US)-guided radiofrequency ablation (RFA) for treating locally recurrent papillary thyroid cancer (PTC). Materials and Methods: We retrospectively analyzed 39 consecutive patients with 61 locally recurrent PTCs (14 males, 25 females; mean ± standard deviation age, 52.8 ± 16.7 years; range 21–92 years) who underwent US-guided RFA with curative intent between September 2008 and April 2012. A subgroup of 24 patients with 37 recurrent PTCs who had a follow-up of at least 10 years were analyzed separately. All patients were followed for changes in lesion size on US and thyroglobulin (Tg) levels at 1, 3, 6, and 12 months after RFA, with follow-up every 6–12 months thereafter. Any complications were documented during the follow-up period. Recurrence-free survival (RFS) rates were assessed using Kaplan-Meier estimates. Long-term outcomes were evaluated in patients with follow-up of at least 10 years. Results: The follow-up period ranged from 7 to 180 months (median 133 months). The RFS rates for the 39 patients at 3, 5, and 10 years were 86.8%, 75.5%, and 60.6%, respectively. Among the 24 patients with 37 recurrent PTCs followed for more than 10 years, the volume reduction rate was 99.9% (range 96%–100%), and the complete tumor disappearance rate was 91.9%. The mean serum Tg level also decreased significantly, from 2.66 ± 86.5 mIU/L before ablation to 0.43 ± 0.73 mIU/L (P < 0.001) at the final follow-up. In 14 (58.3%) of the 24 patients, Tg levels were undetectable (below 0.08 mIU/L) at the last follow-up. No life-threatening or delayed complications were observed during the 10-year follow-up period. Conclusion The high RFS throughout the follow-up period, with efficacy and safety lasting beyond 10 years, supports USguided RFA as a valuable option for local control of recurrent PTCs.

Active surveillance (AS) has been widely adopted as an alternative to immediate surgery owing to the indolent nature and favorable outcomes of papillary thyroid microcarcinoma (PTMC). AS is generally recommended for tumors measuring ≤1 cm without aggressive cytological subtypes, risk of gross extrathyroidal extension (ETE), lymph node metastasis (LNM), or distant metastasis. AS requires careful patient selection based on various patient and tumor characteristics, and ultrasound (US) findings. Moreover, during AS, regular US is performed to monitor any signs of tumor progression, including tumor growth, new US features of potential gross ETE, and LNM. Therefore, appropriate imaging-based assessment plays a crucial role in determining whether AS or surgery should be pursued. However, detailed recommendations concerning US evaluation are currently insufficient, necessitating the formulation of this guideline. The Korean Society of Thyroid Radiology has developed a consensus statement for low-risk PTMC, covering US assessment methods when considering AS as a management option and conducting follow-up imaging tests during AS. This guideline aims to provide optimal scientific evidence and expert opinion consensus regarding a standardized US-based assessment protocol for low-risk PTMC.