Importance: Papillary microcarcinomas of the thyroid (mPTCs) account for an increasing proportion of thyroid cancers in past decades. The use of radiofrequency ablation (RFA) has been investigated as an alternative to surgery. The effectiveness and safety of RFA has yet to be determined.
Objective: To evaluate the effectiveness and safety of RFA for low-risk mPTC.
Data sources: Embase, MEDLINE via Ovid, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and the top 100 references of Google Scholar were searched from inception to May 28, 2021.
Study selection: Articles reporting on adult patients with mPTC treated with RFA were included. Studies that involved patients with pre-ablation lymph node or distant metastases, recurrence of disease, or extrathyroidal extension were excluded. Final article selection was conducted by multiple reviewers based on consensus. The proportion of eligible articles was 1%.
Data extraction and synthesis: This meta-analysis was conducted in accordance with the MOOSE guidelines. Random and fixed-effect models were applied to obtain pooled proportions and 95% CIs.
Main outcomes and measures: The primary outcome was the complete disappearance rate of mPTC. Secondary outcomes were tumor progression and complications.
Results: Fifteen studies were included in this meta-analysis. A total of 1770 patients (1379 women [77.9%]; mean [SD] age, 45.4 [11.4] years; age range, 42.5-66.0 years) with 1822 tumors were treated with RFA; 49 tumors underwent 1 additional RFA session and 1 tumor underwent 2 additional RFA sessions. Mean (SD) follow-up time was 33.0 (11.4) months (range, 6-131 months). The pooled complete disappearance rate at the end of follow-up was 79% (95% CI, 65%-94%). The overall tumor progression rate was 1.5% (n = 26 patients), local residual mPTC in the ablation area was found in 7 tumors (0.4%), new mPTC in the thyroid was found in 15 patients (0.9%), and 4 patients (0.2%) developed lymph node metastases during follow-up. No distant metastases were detected. Three major complications occurred (2 voice changes lasting >2 months and 1 cardiac arrhythmia). Minor complications were described in 45 patients.
Conclusions and relevance: The findings of this systematic review and meta-analysis suggest that RFA is a safe and efficient method to treat selected low-risk mPTCs. Radiofrequency ablation could be envisioned as step-up treatment after local tumor growth under active surveillance for an mPTC or initial treatment in patients with mPTCs with anxiety about active surveillance.