Ultrasonography-guided Radiofrequency Ablation for Solitary T1aN0M0 and T1bN0M0 Papillary Thyroid Carcinoma: A Retrospective Comparative Study.

Objective Ultrasonography-guided radiofrequency ablation (RFA) is used to treat small low-risk papillary thyroid carcinoma (PTC), and has achieved favorable results. However, few studies have compared the outcomes of T1aN0M0 and T1bN0M0 PTC treated with ultrasonography-guided RFA. The objective of this study was to compare the outcomes of patients receiving RFA for solitary T1aN0M0 and T1bN0M0 PTC retrospectively. Methods Patients treated with RFA for solitary T1aN0M0 or T1bN0M0 PTC between April 2014 and December 2019 were retrospectively reviewed. All patients were ineligible for or refused surgery. Our institutional review board approved this study. A total of 262 patients were included after adjustment for propensity score matching between the T1a and T1b groups. Local tumour progression (LTP), LTP-free survival, post-treatment complications, change in tumor volume, and RFA-related parameters were compared between the two groups. Results The LTP rate was 3.82% in both groups, and the LTP and LTP-free survival rates did not significantly differ between the two groups. One patient in group T1b developed transient recurrent laryngeal nerve injury. Significant tumor shrinkage was observed during the follow-up. The rate of tumour disappearance rate was higher in group T1a than in group T1b (81.7% vs. 52.7%, P<0.001). During RFA, the output power and total energy were higher and the duration was significantly shorter in group T1b than in group T1a (P<0.001). Conclusions The outcomes of RFA for the treatment of T1aN0M0 and T1bN0M0 PTC were similar. Therefore, RFA may be an alternative to surgery for the treatment of T1bN0M0 and T1aN0M0 PTCs.