Long-Term Follow-Up Results of Ultrasound-Guided Radiofrequency Ablation for Low-Risk Papillary Thyroid Microcarcinoma: More Than 5-Year Follow-Up for 84 Tumors

Abstract

Background: Despite reports describing favorable short-term results for thermal ablation of thyroid cancer, there remains a need to evaluate long-term results because of its indolent characteristics. The purpose of this study was to evaluate the long-term efficacy and safety of ultrasound (US)-guided radiofrequency ablation (RFA) for low-risk papillary thyroid microcarcinoma (PTMC) over a follow-up period of more than five years. Methods: From a cohort of patients under surveillance after US-guided RFA for primary low-risk PTMC, those with a record of follow-up data of more than five years were selected for this study. Before RFA, all patients underwent US and computed tomography to evaluate the PTMC and the presence of neck metastasis. RFA was performed using thyroid-dedicated electrodes. Follow-up US was performed 6 and 12 months after initial RFA, and then every 12 months. The status of ablated tumors was evaluated according to volume reduction, local tumor progression, newly developed cancers, lymph node (LN) or distant metastasis, and delayed surgery during follow-up. Complications during the procedure and follow-up period were evaluated. Results: A total of 84 nodules from 74 patients were included in this study. All patients tolerated RFA, and the mean follow-up duration was 72 months. After RFA, complete disappearance rates of 98.8% and 100% were achieved at 24 and 60-month follow-up, respectively. Additional ablations were performed in 13 of 84 tumors. The mean number of RFA sessions was 1.2. There were four newly developed cancers in three patients, and these were also treated with RFA and completely disappeared. During the follow-up period, there was no local tumor progression, no LN or distant metastasis, and no patients underwent delayed surgery. The major complication rate was 1.4% (1/74), and there was no delayed complication or procedure-related death. Conclusions: RFA is effective for treating low-risk PTMC patients, without occurrence of local tumor progression, LN or distant metastasis, delayed complications, procedure-related death, or delayed surgery over more than five years of follow-up.

Image-Guided Thermal Ablation as an Alternative to Surgery for Papillary Thyroid Microcarcinoma: Preliminary Results of an Italian Experience

“…Moreover, the pooled proportion of major complications was extremely low (0.7%), being represented by non-life-threatening voice change ( 9 ). In a recent series of 74 patients treated with RFA for 84 PTMC and followed for at least 5 years Cho et al., showed a disappearance rate of 100% at 60 months, no local tumor progression, no lymph node or distant metastasis, and no need for delayed surgery ( 47 ). Additional ablations were performed in 13 of 84 tumors.…”

Radiofrequency for benign and malign thyroid lesions

“…Thermal ablation's early results, 19 , 32 on selected patients, encouraged prospective trials 20 , 22 to investigate the long-term results of the PTMC treatment. These manuscripts demonstrated lower incidence of complications, morbidity and cost when compared to surgery.…”

“…Type of energy used, follow-up, reduction and recurrences. Ref Technique Patients (N) Nodules (N) Initial vol (mm 3 ) Reduction (%) FU (m) Recurrence (N) New foci (N) Zhang, M et al 2020 22 RFA 94 94 175.9 ± 228.3 – 72 1 0 Wu, R et al 2020 21 RFA 198 204 99.4 ± 82 99.8 ± 1 25.9 – – Cho, SJ et al 2020 20 RFA 74 84 20 (1–234) 100 60 0 4 Yue, W et al 2014 33 MWA 18 18 89.5 ± 20.1 90 12 0 0 Cui, T et al 2019 34 MWA 185 206 100.1 ± 92.9 98.6 ± 3.6 36 0 1 Zhang et al 2018 LA 64 64 41 ± 40 100 25.7 0 0 RFA: radiofrequency ablation; MWA: microwave ablation; LA: laser ablation. …”

“…Recently, three papers addressing long-term follow-up came out with important results. Cho et al 20 described retrospectively 84 malignant thyroid nodules and followed them for 72 months resulting in a 100 reduction rate with 60 months. Additional ablation was necessary in 15.4% of the cases, also 3 out of 74 patients discovered new papillary carcinoma foci and were treated with RFA.…”

“…The most common one is pain, ranging from 2% to 60% although severe pain is unusual. 20 , 23 , 24 , 25 , 26 Some authors use sedation to perform more extensive ablation. Direct damage to critical structures of the neck is a risk during ablation procedures and its likelihood depends on the size and position of the lesion.…”