Single-Session Treatment of Benign Cystic Thyroid Nodules with Ethanol versus Radiofrequency Ablation: A Prospective Randomized Study

Abstract

To compare volume reduction of single-session ethanol ablation (EA) and radiofrequency (RF) ablation for cystic thyroid nodule treatment. All patients gave written informed consent to participate in this prospective institutional review board-approved study. From May 6, 2010, to August 8, 2011, in this single-institutional, noninferiority trial, 50 patients, each with a single cystic thyroid nodule, were randomly assigned to EA (25 patients; mean age for women, 45.7 years, and for men, 37.5 years) or RF ablation (25 patients; mean age for women, 45.1 years, and for men, 43.7 years) treatment. Internal fluid was aspirated prior to EA or RF ablation. Primary end point was the volume reduction ratio (percentage) at 6-month follow-up; the noninferiority margin was chosen as -8% (EA minus RF ablation). Secondary end points included therapeutic success rate, improvement of symptoms and cosmetic problems, and number of major complications. Analysis was performed primarily in intention-to-treat manner. A one-sided 95% confidence interval (CI) for the mean difference in volume reduction ratio 6 months after treatment was calculated to test for noninferiority. Subsequent superiority comparison of EA with RF ablation on a condition of establishment of the noninferiority of EA to RF ablation was preplanned and used two-sided 95% CI of the outcome difference. The mean volume reduction was 96.9% in EA and 93.3% in RF ablation (n = 21 for each) (difference, 3.6%; lower bound of the one-sided 95% CI of the difference, 1.2%), thus demonstrating the noninferiority of EA to RF ablation. Two-sided 95% CI of the outcome difference was 0.7% to 6.5%, demonstrating significant superiority of EA to RF ablation. All patients demonstrated therapeutic success (P > .99). Mean symptom and cosmetic scores showed no significant difference in either group (P = .806 and P = .682, respectively). There were no major complications (P > .99). EA may be the first-line treatment modality for cystic thyroid nodules, which has comparable therapeutic efficacy to, but is less expensive than, RF ablation.