Clinical efficacy of ethanol ablation and microwave ablation on cystic or predominantly cystic thyroid nodules: A retrospective comparative study

Objective: To compare the efficacy and safety of ethanol ablation (EA) and microwave ablation (MWA) in the treatment of cystic or predominantly cystic thyroid nodules. Methods: : Clinical data of patients with cystic or predominantly cystic thyroid nodules intervened with EA or MWA in the Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine from January 2013 to November 2019 were retrospectively analyzed. The patients were divided into EA group (n=30) and MWA group (n=26). The volume and volume reduction rate of thyroid nodules before ablation, and at 3 months and 12 months after ablation were compared between the two groups. The effective rate and incidence of adverse events in both groups were recorded. Results: The median volume reduction rate at 3 months after ablation was significantly higher in EA group than MWA group (81.30% vs. 75.76%, P =0.010), while no significant difference was detected at 12 months (93.39% vs. 89.34%, P =0.141). There was no significant difference in effective rate between the two groups during the follow-up ( P >0.05). The maximum diameter of the thyroid nodule (2.96 ± 0.78 cm vs. 3.78 ± 1.02 cm, P <0.05), mean volume of thyroid nodule (4.92 [2.93-10.19] ml vs. 8.33 [4.92-15.02] ml, P <0.05) and medical cost (111.73 ± 55.22 USD vs. 2443.79 ± 285.46 USD, P <0.001) were significantly lower in EA group than MWA group, while EA group required more treatment cycles 2.5 [1.0-3.3] times vs. 1 [1.0-1.0] time, P <0.001). Serious adverse events were not reported in both groups. Conclusion: EA and MWA are both effective and safe in the treatment of cystic or predominantly cystic thyroid nodules. Although EA is more cost-effective, it requires more times of treatment and may poses a higher risk of postoperative pain compared with MWA.