US-guided percutaneous radiofrequency versus microwave ablation for benign thyroid nodules: A prospective multicenter study.

e17593 Background: To evaluate the clinical outcomes between radiofrequency ablation (RFA) and microwave ablation (MWA) in treating benign thyroid nodules (BTNs) with a prospective multicenter study. Methods: The prospective multicenter study achieved the registration of Chinese Clinical Trial Registry (Number: ChiCTR-ONRC-13003087). From January of 2013 to December of 2015, the total number of 1,252 patients with 1351 benign thyroid nodules (BTNs) at eight participating institutions was enrolled in the multicenter study. The ablation devices were applied in the study including RFA system of VIVA RF generator (VIVA RF generator, STARmed, Goyang, Korea) and MWA system of KY-2000 2450MHz microwave system (KY-2000, Kangyou Medical, Nanjing, China). All the procedures of RFA or MWA were performed under ultrasound (US) guidance in each center. Results: The number of target nodules treated by RFA and MWA were 687 in 649 cases and 664 in 603 cases, respectively. For the estimation of efficacy, the mean maximal diameter reduction ratios (MDRRs) of RFA vs. MWA groups at the 3rd, 6th, 12th month and last follow-up were 36.4±17.3% vs. 36.0±23.0% (p = 0.765), 54.1±22.7% vs. 49.3±28.0% (p = 0.005), 64.5±22.1% vs. 57.9±40.1% (p = 0.008) and 65.5±26.0% vs. 58.2±33.5% (p = 0.028), respectively. The mean volume reduction ratios (VRRs) of RFA vs. MWA groups at the 3rd, 6th, 12th month and last follow-up were 67.6±20.3% vs. 64.4±43.5% (p = 0.143), 84.1±13.5% vs. 78.4±48.2% (p = 0.016), 89.6±20.0% vs. 82.5±49.7% (p = 0.035) and 91.3±12.6% vs. 81.1±70.4% (p = 0.045), respectively. For the estimation of safety, for all the complications and side effects encountered at the peri-ablation and follow-up period in two groups, the major, minor complication and side effect rates of RFA vs. MWA group were all no statistical significances with 4.78% vs. 6.63% (p = 0.156), 2.00% vs. 2.49% (p = 0.562) and 4.93% and 4.64% (p = 0.812), respectively. Conclusions: As a conclusion of the prospective multicenter study, both RFA and MWA under US guidance percutaneously are safe and effective techniques for selected patients with BTNs. Larger MDRR and VRR can be achieved in RFA group than the ones in MWA group at 6-month and later follow-up. Clinical trial information: ChiCTR-ONRC-13003087.