Current Status and Challenges of US-Guided Radiofrequency Ablation of Thyroid Nodules in the Long Term: A Systematic Review

SIMPLE SUMMARY: Ultrasound (US)-guided minimally-invasive techniques, such as radiofrequency ablation (RFA) have emerged as an alternative treatment to surgery for benign and malignant thyroid nodules. Based on a systematic literature search, here we report the long-term outcomes of thyroid RFA. Available data show that US-guided RFA significantly reduced benign thyroid nodules and destroyed most PTMC, and this was generally maintained for at least 5 years after the initial treatment. Further studies addressing the risk of regrowth in patients with benign thyroid nodules, as well as the risk of recurrence in patients with PTMC are needed. ABSTRACT: Background: US-guided minimally-invasive techniques, such as radiofrequency ablation (RFA) have emerged as an alternative treatment for benign and malignant thyroid nodules. This systematic review aims to provide an overview on the long-term outcomes of US-guided RFA in patients with benign and malignant thyroid nodules. Methods: We systematically searched PubMed/MEDLINE, EMBASE, and Scopus to identify articles reporting the outcomes of thyroid RFA after a follow-up of at least 3 years. Results: A total of 20 studies met the inclusion criteria and were included in the review. In patients with benign thyroid nodules, RFA significantly reduced nodule volume and this was generally maintained for the following 5 years. However, a small but not negligible proportion of nodules regrew and some of them required further treatments over time. In patients with malignant nodules, RFA has been used not only to treat differentiated thyroid cancer (DTC) neck recurrences, but also to treat papillary thyroid microcarcinoma (PTMC). In most patients with PTMC, RFA led to complete disappearance of the tumor. When it was compared to surgery, RFA was not inferior in terms of oncologic efficacy but it had a lower complication rate. However, RFA did not allow for final pathology, disease staging and accurate risk stratification. Conclusions: US-guided RFA significantly reduces benign thyroid nodules and destroys most PTMC, and this is generally maintained for at least 5 years after the initial treatment. Further studies addressing the risk of regrowths in patients with benign thyroid nodules, as well as the risk of recurrence in patients with PTMC are needed.