Comparative efficacy and safety of thermal ablation versus surgery in thyroid cancer: umbrella review of meta-analyses of observational cohort studies

BACKGROUND: Thermal ablation (TA) is gaining popularity for its minimally invasive nature, especially in specific thyroid cancer subtypes, but its efficacy remains inconclusive and it isn't recommended for thyroid cancer treatment. This umbrella review aimed to evaluate the efficacy and safety of TA compared to surgery, focusing on recurrence, complications, and quality of life. METHODS: A systematic search of PubMed, Embase, Web of Science, and Cochrane Library (up to November 2024) was conducted to identify observational cohort studies comparing perioperative and long-term outcomes between TA and surgical resection. Data were extracted for effect estimates, heterogeneity, and quality assessed using A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) and evidence grading criteria. RESULTS: Eight meta-analyses (n = 7025 patients) were included, with median follow-up durations of 25 months. Across overlapping datasets, TA, including radiofrequency (RFA), microwave (MWA), and laser ablation (LA) demonstrated consistent perioperative advantages compared with surgery in low-risk papillary thyroid carcinoma (PTC), predominantly papillary thyroid microcarcinoma (PTMC, T1aN0M0). Summary estimates from high-quality meta-analyses showed that showed that TA was associated with a significantly lower overall complication rate (OR [Odds Ratio], 0.43; 95%CI, 0.23-0.80), shorter operation time (MD [Mean Difference], - 64.33; 95%CI, - 71.12--55.53), and lower hospital costs (MD, - 0.84; 95%CI, - 1.06--0.62). These trends were consistently observed across RFA and MWA subgroups, whereas LA data remained limited. In contrast, long-term oncologic outcomes, including recurrence (OR, 1.17; 95%CI, 0.67-2.02) and lymph node metastasis (RR [Risk Ratio], 0.77; 95%CI, 0.44-1.36) showed no statistically significant differences between TA and surgery, with wide confidence intervals indicating substantial uncertainty. Across the included meta-analyses, 38.9% of associations showed high heterogeneity (I2 > 50.0%), and the evidence quality was rated as moderate to low due to limited follow-up durations and the predominance of observational cohort data. CONCLUSION: TA offers short-term benefits such as fewer complications, shorter procedures, and lower hospital burden compared with surgery in low-risk PTMC. Yet, due to the predominance of observational data, limited follow-up, and significant heterogeneity, the current evidence remains insufficient to determine its long-term oncologic safety. TA should therefore be viewed as a selective treatment option for carefully chosen low-risk patients, pending confirmation from large, randomized studies with standardized endpoints and extended follow-up.