Long-Term Outcomes of Radiofrequency Ablation for Benign Thyroid Nodules of Different Sizes: Implications of Regrowth and New Growth.

Radiofrequency ablation is an effective treatment for benign thyroid nodules. Since initial nodule volume may impact the efficacy of radiofrequency ablation, this study evaluated its long-term outcomes across varying nodule sizes, focusing on regrowth, new growth, and clinical management implications. This retrospective study included 160 patients who underwent thyroid radiofrequency ablation for benign thyroid nodules at a Taiwanese tertiary center between July 2016 and April 2018. Patients were classified into three groups based on nodule size: small (< 10 mL), medium (10-30 mL), and large (> 30 mL). Treatment efficacy was assessed over a period of up to 5 years, focusing on volume reduction rate, regrowth, residual volume, and new growth. The initial ablation rate of all benign thyroid nodules was 99.46%. After the 5-year follow-up, the volume reduction rate was 92.96%. The small nodule group demonstrated the highest volume reduction rate. The incidence of increased residual vital volume was 3.57%. The overall regrowth rate was 9.82%, with a mean time to regrowth of 2.8 years. No nodules required retreatment due to regrowth. New growth was observed in 22.32% of patients, with the highest incidence in the large nodule group (34.29%). Radiofrequency ablation is effective in the long-term management of benign thyroid nodules across various sizes, achieving substantial volume reduction rate with minimal complications. For larger nodules, monitoring for new growth warrants increased attention and may serve as a critical parameter indicative of recurrence and the potential need for retreatment.