Patients with indeterminate thyroid nodules who underwent radiofrequency ablation following functional imaging screening experienced sustained nodule reduction and symptom improvement, with a high probability of remaining free of local treatment failure at 3 years, according to a retrospective cohort study.
Researchers evaluated 109 patients with Bethesda category III or IV thyroid nodules treated with radiofrequency ablation (RFA) in Taiwan between 2018 and 2024. All of the patients had indeterminate cytology on at least two assessments and underwent preprocedural risk stratification with technetium-99m–methoxyisobutylisonitrile scintigraphy or fluorine-18–fluorodeoxyglucose positron emission tomography. The cohort consisted of patients who met predefined imaging criteria and elected RFA after declining surgery. The median follow-up was 2.2 years.
The primary outcome was local treatment failure, defined as nodule regrowth, an increase in vital volume, or persistent indeterminate cytology during follow-up. The secondary outcome was complete disappearance of the treated nodule. The researchers also assessed volume reduction, symptom and cosmetic scores, and thyroid-related laboratory measures.
Local treatment failure occurred in about 14% (n = 15/109) of the patients. The estimated probability of remaining free of local treatment failure at 3 years was 85%. Complete disappearance of the nodule occurred in 8% (n = 9) of the patients, corresponding to a 3-year cumulative incidence of 7%.
Most of the local treatment failures were related to persistent indeterminate cytology. For instance, 10 of the patients had repeat Bethesda III or IV findings on follow-up fine-needle aspiration, 5 of them experienced nodule regrowth, and 1 of them had an increase in vital volume. Among those with regrowth, 3 patients underwent repeat RFA and 2 patients continued active surveillance. No patient required surgery during follow-up.
Nodule volume declined progressively throughout follow-up. Volume reduction reached 56% at 3 months, 75% at 1 year, and 91% at 3 years. Symptom and cosmetic scores also improved over time. Free thyroxine and thyroglobulin levels decreased; while total triiodothyronine, thyroid-stimulating hormone, and antithyroid antibody levels remained stable.
Baseline nodule size was the strongest predictor of outcomes. Larger nodules were more likely to experience local treatment failure and less likely to disappear completely. The researchers reported that 93% of nodules smaller than 3 cm remained free of local treatment failure at 3 years. No nodule larger than 2.1 cm achieved complete disappearance during follow-up.
Safety outcomes were generally favorable. Five of the patients experienced vocal cord palsy–related hoarseness. Four recovered completely within 3 months, while 1 patient had persistent but improving vocal cord dysfunction and was classified as having a major complication. No local or distant metastases were observed during follow-up. Among the 97 patients who underwent posttreatment fine-needle aspiration, 0% had Bethesda category V or VI cytology.
The researchers stated that the findings should be interpreted within the context of several limitations. The study was retrospective and conducted at a single center. The cohort was highly selected, including only patients who met functional imaging criteria and chose RFA rather than surgery. In addition, the researchers did not directly compare outcomes with surgery, active surveillance, or patients who did not undergo imaging-based screening. They noted that the proposed nodule-size thresholds require external validation and that longer follow-up is needed to assess long-term outcomes.
In their conclusion, wrote lead study author Ling-Chieh Shih, of Kaohsiung Chang Gung Memorial Hospital in Taiwan, and colleagues wrote that
“RFA demonstrated acceptable outcomes with volume reduction and symptom relief, particularly in patients with nodules [less than] 3 cm.” They added that baseline nodule diameter “may serve as a practical factor for patient selection and counseling,” wrote lead study author Ling-Chieh Shih, of the Department of Diagnostic Radiology at the Kaohsiung Chang Gung Memorial Hospital at the Chang Gung University College of Medicine in Taiwan, and colleagues.
The study authors reported no conflicts of interest. No funding was reported.
Source: Korean Journal of Radiology
