Radiofrequency ablation for papillary thyroid cancer located in isthmus: comparison with that originated in thyroid lobe.

[PURPOSE] To analyze the outcomes of radiofrequency ablation (RFA) for isthmus papillary thyroid cancer (PTC) versus PTC originating from the lobes.

[METHODS] Patients with solitary low-risk PTC treated with RFA between July 2014 and December 2019 were retrospectively reviewed. This study was approved by our institutional review board. Of the 562 patients, 104 and 458 had PTCs located in the thyroid isthmus and thyroid lobes, respectively. Local tumor progression (LTP), LTP-free survival (LTPFS), changes in tumor volume, and complications were compared between the two groups using propensity-score matching (PSM).

[RESULTS] The isthmic and lobar groups showed no significant differences in LTP (2.9% vs. 3.8%), new PTC (2.9% vs. 2.9%), persistent lesions (0.0% vs. 0.2%), or LTPFS after PSM. Before PSM, the two groups showed significant differences in the volume reduction ratio (VRR) of the ablated tumors at 1, 3, 24, 30, and 48 months after RFA, but no differences between the two groups were observed in tumor volume, VRR, or disappearance rate after PSM ( > .05). One patient in the isthmic group presented with coughing, while another complained of hoarseness. Complications did not differ significantly between the two groups ( > .05).

[CONCLUSIONS] The outcomes of RFA for patients with low-risk PTC in the thyroid isthmus and thyroid lobes were similar. Therefore, RFA may serve as an alternative treatment option for patients with low-risk isthmic PTC.