Mid-to Long-term Outcomes After Single Radiofrequency Ablation of Nontoxic and Toxic Thyroid Nodules

OBJECTIVE: To evaluate the mid- to long-term recurrence rates after a single radiofrequency ablation (RFA) of benign thyroid adenomas. DESIGN: Retrospective review of data collected in a standardized prospective database. SETTING: Single-center thyroid clinic in Austria. PARTICIPANTS: Eight hundred ninety-six consecutive patients with either nontoxic nodules (n = 765) or toxic adenomas (n = 131). INTERVENTION: Mono- or bipolar RFA under local anesthesia. MAIN OUTCOME MEASURES: Recurrence defined as increase in nodule size after RFA treatment by ≥50% from its smallest volume (nontoxic adenomas) or relapse of hyperthyroidism (toxic adenomas). RESULTS: Follow-up periods of 3 years or more were available for 437 nontoxic and 58 toxic adenomas. The median baseline volume was 10.1 mL [interquartile range (IQR) 5.5-20] for nontoxic and 7.2 mL (IQR 4.2-14.3) for toxic nodules. Solid or predominantly solid nodules comprised 81% and 93%, respectively. After 1, 3, and 5 years, the average nodule volume decreased by 79%, 82%, and 86% for nontoxic and by 84%, 88%, and 89% for toxic nodules, remaining stable afterwards.In 54 patients (7.1%) with nontoxic nodules, regrowth occurred, with a cumulative incidence rate of 17.3% over a maximum of 8 years. Among 15 patients (11.5%) with toxic adenomas, recurrence of hyperthyroidism was observed over 7 years (21.6% cumulative incidence). Fourteen of these patients became euthyroid after low-dose radioiodine treatment (n = 11) or a second RFA (n = 3). Documented complications included 2.3% moderate and 0.3% severe cases. CONCLUSION: In our cohort, a single RFA treatment resulted in favorable mid- to long-term outcomes in 83% of nontoxic and 78% of toxic adenoma patients, with an acceptable complication rate.