Efficacy, safety, and risk factors of thermal ablation for follicular thyroid neoplasms: a multicentric study

Purpose To assess the efficacy and safety of thermal ablation (TA) in managing follicular thyroid neoplasms (FN). Methods This multicenter retrospective study involved participants diagnosed with FN across nine hospitals, undergoing microwave ablation or radiofrequency ablation from January 2014 to January 2024. Primary outcomes assessed were technical success and disease progression, with secondary outcomes including tumor size and volume changes, complete tumor disappearance, complications, and side effects. Subgroup analyses aimed to identify factors influencing tumor progression and complete disappearance. Results The study enrolled 375 patients (mean age: 43.2 years +/- 14.9 [standard deviation]; 298 women) with 482 FNs, tracked over an average of 23.6 months, achieving a 100% technical success rate. Disease progression was observed in 4.8% (18/375) of patients, with a local recurrence rate of 3.7% (14/375) and new neoplasm occurrence of 1.1% (4/375). Multifocal neoplasms emerged as an independent risk factor for disease progression (hazard ratio [HR], 3.48; 95% CI, 1.16-10.45; P = 0.026). Tumor volume significantly reduced (P < 0.001), particularly within 1-3 months post-ablation, with complete tumor disappearance observed in 10.4% (39/375) of cases, more likely in tumors smaller than 2 cm (HR, 0.11; 95% CI, 0.06-0.23; P < 0.001). Complications occurred in 2.9% of patients, with major events in 2.1% and minor in 0.8%. Conclusion TA is a safe and efficacious method for treating FN, showing low rates of disease progression and complications. Optimal outcomes may be achieved in patients with unifocal FN and neoplasms under 2 cm.