Early Outcomes of Thermal Ablation for Low-Risk Papillary Thyroid Cancer: A Multicenter Study from Latin American Interventional Thyroidology Association (LAITA)

Background: Thermal ablation has emerged as a minimally invasive alternative for low-risk papillary thyroid cancer (PTC). However, data from Latin America remain scarce. This multicenter study evaluated the early efficacy and safety of thermal ablation for low-risk PTC across multiple Latin American centers. Methods: Retrospective cohort study including 251 patients with 252 tumors (T1N0M0 PTC, ≤2 cm) treated with ultrasound-guided radiofrequency ablation (RFA) at 12 centers across 6 Latin American countries from January 2019 to June 2025. Primary outcomes were complete tumor disappearance, disease progression, and complications. Results: Median age was 45.5 years (interquartile range [IQR]: 36.5–56), with 74.2% female patients. Median tumor size was 6.7 mm (IQR: 5–8); 92.1% were T1a (≤10 mm). After a median follow-up of 18 months (IQR 12–24, range 12–72), complete tumor disappearance was achieved in 89.7% overall (226/252), reaching 97.0% in tumors with ≥18 months and 100% with ≥36 months of follow-up. Tumor persistence was observed in 10.3% (26/252) at last follow-up, with no lymph node or distant metastases. The overall complication rate was 2.4% (6/252), all consisting of transient dysphonia. On multivariable analysis, tumor size >10 mm was independently associated with a lower likelihood of complete tumor disappearance (adjusted odds ratios [OR] 0.23 [CI: 0.07–0.78]), whereas follow-up >12 months was associated with a higher likelihood (adjusted OR: 11.33 [CI: 3.61–35.6]). A supplementary post hoc analysis suggested a possible association between higher general operator volume (≥250 RFA procedures) and complete disappearance. Conclusions: RFA demonstrates excellent efficacy and acceptable safety for T1a low-risk PTC in Latin American patients, with outcomes comparable with other series, supporting it as a viable alternative to surgery or active surveillance in selected patients. Efficacy for T1b tumors was lower and based on a small number of cases; ablation of T1b disease should therefore be regarded as requiring further investigation, ideally within the framework of a clinical trial.