Comparing the efficacy of using radiofrequency ablation versus microwave ablation for the retreatment of benign...

The comparative efficacy of radiofrequency ablation versus microwave ablation for the retreatment of benign thyroid nodules remains less known. This study compared the 12-month volume reduction rate after retreatment with radiofrequency ablation versus microwave ablation, spaced ≥12 months from the last thermal ablation, for benign, predominantly solid thyroid nodules.

Consecutive patients undergoing radiofrequency ablation or microwave ablation as a retreatment were considered. The inclusion criteria were (1) cytologically benign, predominantly solid (≥80%) thyroid nodules; (2) previous thermal ablation; (3) retreatment spaced at least 1 year from the last thermal ablation; (4) completed 12-month follow-up after retreatment. Patients receiving further thermal ablation, surgery, or radioiodine within 12 months of retreatment were excluded. The primary outcome was 12-month volume reduction rate after retreatment = volume before retreatment - 12-month volume/volume before retreatment × 100%. Complications, compressive, and cosmetic symptoms were compared.

From 2022 to 2024, 46 nodules (radiofrequency ablation: 23, microwave ablation: 23) from 46 patients were eligible for analysis. Baseline nodule volumes prior to any thermal ablation (radiofrequency ablation: 33.6 mL [20.6-50.7 mL] versus microwave ablation: 31.0 mL [17.2-47.8 mL], P = .442) and prior to retreatment (radiofrequency ablation: 17.0 [12.7-25.0 mL] vs microwave ablation: 17.3 mL [12.8-27.5 mL], P = .717) were comparable. The median interval to retreatment was 23 months (17-39). The overall 12-month volume reduction rate following retreatment was 76.9% (60.7%-82.3%), with no significant difference between radiofrequency ablation and microwave ablation (72.4% [56.0-85.1%] vs 77.3% [60.7-81.5%], P = .915). The final volume reduction rate achieved from baseline prior to any thermal ablation was 86.8% (69.3-92.0%) and comparable between groups (radiofrequency ablation: 87.7% [62.9%-93.4%] versus microwave ablation: 85.3% [75.1%-89.7%], P = .852). No vocal cord palsy or hematoma occurred. Cosmetic symptoms improved after retreatment (P = .005).

For large benign solid thyroid nodules that were previously treated with thermal ablation, retreatment at ≥12 months later led to further nodule shrinkage. Retreatment with radiofrequency ablation or microwave ablation at this time interval was comparably effective and safe.