Microwave ablation of thyroid nodules: effects on recurrence and outcome

Abstract

Background: Microwave ablation developed into an accepted treatment for benign thyroid nodules. Definition and risk factors for recurrence are under discussion. We assumed recurrence in case of a second procedure for the same reason or if clinical symptoms reappear after initial relief, and analyzed our prospectively collected data for risk factors and outcome. Methods: Indications included benign thyroid nodules (n=24), cystic nodules (n=9), autonomous functioning nodules (n=9), recurrent cancer (n=3) and Basedow’s disease (n=2). For microwave ablation, a CE certified generator was used. All procedures were conducted under ultrasound control and with general anesthesia or mild sedation. Followup included ultrasound, laboratory parameters and a standardized questionnaire. Results: A total of 47 patients were enrolled into the study. Among them were 19 cases with risk factors for recurrence which were defined as nodule size exceeding 4 cm with or without cystic appearance. Recurrence occurred in 9 cases leading to conventional hemithyreoidectomy (n=1), reablation (n=5) or sclerotherapy (n=1). The association of recurrence with the presence of a risk factor was statistically significant (p<0,001, Chi square test). In case of recurrence, statistically significant less energy was deployed in comparison to successful MCT (0,39 +/- 0,31 kJ/mL vs. 1,57 +/- 2,37 kJ/mL, p< 0,005, t-test). Conclusion: Recurrence is a common problem following microwave ablation of thyroid nodules. Nodules > 4 cm and cystic disease seem to predispose for treatment failure. Further studies are required to define recurrence and the best indications for microwave ablation of thyroid nodules.