Introduction:
Radiofrequency ablation (RFA) for symptomatic, benign thyroid nodules was started in Rijnstate Hospital in January 2015. So far, we have treated 110 subjects with non-toxic nodules. According to the current literature a mean nodule volume reduction of 80% should be achievable, in experienced hands.

Aim:
To evaluate the 6-month efficacy of RFA in reducing thyroid nodular volumes and nodule-related symptoms, and to assess the degree of experience required to meet the current international standard.  

Patients and Methods:
RFA was performed in an outpatient setting, after local anesthesia, with an internally cooled 18-gauge electrode with a 10 mm active tip, using the moving shot technique and the transisthmic approach. Only patients with a follow-up of at least 6 months after first RFA were included.

Results:
Sixty-five patients with benign thyroid nodules, ranging in age from 18.7 – 84.2 years, were treated with RFA and had a follow up of at least 6 months. Nine percent of patients had a history of hemithyroidectomy. All patients were euthyroid at baseline. Nodule volume reduction was achieved in all but three patients. The efficacy of treatment improved markedly with increasing experience. Mean volume reduction was 26% in the first ten patients, 52% in the second ten, 71% in fifth ten, etc. In most patients, a volume reduction of 30% was sufficient to experience a significant reduction in nodule-related symptoms. The achieved results indicate that at least 40 procedures are required to guarantee an individual  volume reduction of 50% with high likelihood. The learning curve based on current results predicts that at least 125 procedures are needed to achieve a mean volume reduction of 80%

Conclusion:
RFA is a highly effective, non-surgical, treatment in patients with symptomatic, benign thyroid nodules. However, substantial technical experience is required to achieve the international standard, defined as a mean volume reduction of 80%.