The efficacy and safety of microwave ablation in benign large thyroid nodules (≥4 cm)

OBJECTIVE: The objective of this study was to evaluate the safety and efficacy of ultrasound-guided single-session microwave ablation for benign thyroid nodules >4 cm by comparing outcomes with smaller nodules (<4 cm). METHODS: This retrospective single-center study (2016-2023) analyzed 1,107 patients with 1,463 pathologically confirmed benign thyroid nodules stratified by maximum diameter into four groups: ≤20, 20-40, 40-60, and ≥60 mm. Standardized follow-up was performed at 1, 3, 6, 12, and 24 months post-microwave ablation and then annually. Volume reduction ratio, maximum diameter reduction ratio, recurrence rate, and complications were assessed. RESULTS: The cohort (127 males and 980 females) had a mean age of 45.8 ± 12.7 years and a mean maximum nodule diameter of 28.9 ± 14.6 mm. Complication rates significantly increased with nodule size (2.59, 5.55, 13.36, and 16.67%, respectively; P < 0.001). Technical efficacy exceeded 90% across all groups (P > 0.05). Volume reduction ratio improved significantly over time across all groups, with statistical differences at 1, 6, 12, and ≥24 months (all P < 0.001) but not at 3 months (P = 0.085). The ≤20 mm group achieved the highest volume reduction ratio at ≥24 months (96% ± 14%). CONCLUSION: Ultrasound-guided single-session microwave ablation is safe and effective for large benign thyroid nodules, providing significant volume reduction with acceptable complication profiles while reducing treatment burden.