US-guided microwave ablation of low-risk papillary thyroid microcarcinoma: Longer-term results of a prospective study

Abstract

Background: Papillary thyroid microcarcinoma (PTMC) has become a main cause of theextremely high incidence of thyroid carcinoma. This study aimed to evaluate the longer-termeffectiveness of ultrasound (US)-guided microwave ablation (MWA) for treatment of low-riskPTMC with a large population.Methods: This prospective study was approved by ethics committee of our institution. MWAwas performed under US-guidance for 119 unifocal PTMC patients without clinically cervicalor distant metastasis. The target ablation zone exceeded the tumor edge judged by contrastenhanced US to avoid marginal residue and recurrence. US and thyroid function evaluationwere followed at 1, 3, 6, and 12 months after treatment and every 6 to 12 months thereafter.Any adverse event associated with MWA was evaluated.Results: The follow-up duration after MWA was 37.2 ± 20.9 months (range 12-101 months).Tumor volume decreased significantly from 1.87 ± 1.03 mL immediately after MWA to0.01 ± 0.04 mL at the final evaluation (P < 0.001), with a mean volume reduction ratio of99.4 ± 2.2% and 107 cases (93.9%) got complete remission. A patient was detected with cervicallymph node metastasis at 26-month follow-up and underwent 1 additional MWA treatmentsuccessfully. No distant metastasis was observed. All the acquired histological pathologyresults confirmed the absence of residual or recurrent tumor cells after MWA. No delayedcomplications associated with MWA were encountered for all patients.Conclusions: Percutaneous MWA is technically feasible for complete PTMC destruction andshowed well longer-term effectiveness; thus, it seems to be an effective nonsurgical therapy tocomplement the current recommendation for selected low-risk PTMC patients.