Follow-up of microwave ablation in papillary thyroid carcinoma less than or equal to 2 cm with minimal extrathyroid extension evaluated by CEUS: a propensity score matching study with surgical treatment

Background: Surgical treatment for papillary thyroid carcinoma (PTC) less than or equal to 2 cm with minimal extrathyroid extension (mETE) has a relatively good therapeutic effect, but it is still unknown whether microwave ablation (MWA) can achieve the same therapeutic effect. Objective: To compare the efficacy of MWA with surgery for PTC less than or equal to 2 cm with mETE evaluated by contrast-enhanced ultrasound. Methods: A retrospective analysis of 633 PTC less than or equal to 2 cm with mETE patients was conducted, including 215 treated with MWA (MWA group, MG) and 418 with surgery (operation group, OG). After propensity score-matching (PSM), the basic characteristics – treatment time, complication rates, hospital stays, recurrence and metastasis rates – were compared between the two groups. According to location, 215 patients in the MG were further divided into the isthmus subgroup (ISG) (61 patients) and nonisthmus subgroup (NSG) (154 patients). After PSM, the parameters for comparison are the same as those in the MG and OG. Results: After PSM, no significant differences in recurrence or metastasis rates were observed between the MG and OG. The treatment time and hospital stays in the MG were significantly lower than the OG ( P < 0.001 and P < 0.001). The proportion of abnormal thyroid function and serum calcium concentrations in the OG was significantly greater than the MG ( P < 0.001 and P = 0.044). In subgroup, no significant differences in recurrence or metastasis rates were observed between the ISG and NSG after PSM. The mean treatment time in the MG was significantly shorter than the NSG ( P < 0.001). The ablation volume in the ISG was significantly lower than the NSG ( P < 0.001). The incidence of hoarseness in the NSG was higher than in the ISG ( P = 0.042). Conclusion: MWA is safe and effective for treating PTC less than or equal to 2 cm with mETE, regardless of whether it is located in isthmus.