Thyroid Nodule RFA vs Microwave Ablation: US Study of 351 Nodules

A US study comparing radiofrequency ablation (RFA) and microwave ablation (MWA) for benign thyroid nodules over one year at a single hospital was published on October 10, 2026 in the journal Endocrine. Researchers at Columbia University Irving Medical Center in New York reviewed 351 benign nodules in 271 patients. At 12 months, the median volume reduction ratio was 77.8% after RFA and 70.8% after MWA, with no statistically significant difference.

The takeaway is not that one method wins, but that both shrank benign nodules to a similar degree. The study was not randomized, the microwave group was small, and many nodules had no 12-month measurement, so the results need careful interpretation.

What is new: six years of data from one US hospital

In thermal ablation of a thyroid nodule, a thin needle is inserted through the skin of the neck and guided by ultrasound into the nodule, where heat destroys the tissue. The treated tissue is gradually absorbed over the following months, and the nodule shrinks. RFA produces heat with electrical current, while MWA uses electromagnetic waves. Because it is image-guided and needs no incision, it belongs to the same family as the local treatments of interventional radiology (IVR).

Most head-to-head data so far have come from Asia and Europe, with little from North America. The Columbia team (first author Thornton A, senior author Kuo JH) collected nodules ablated at their hospital from 2019 to 2025: 224 patients with 291 nodules in the RFA group and 47 patients with 60 nodules in the MWA group, followed up to 12 months. They compared nodule volume, volume reduction ratio (VRR), symptom scores such as neck pressure, cosmetic scores and complications.

Who is it for

The study included benign nodules confirmed by biopsy that were non-functioning, meaning they did not overproduce thyroid hormone. Cancers and autonomously functioning (hot) nodules were not part of this comparison.

International guidance describes similar candidates.

• Symptoms or cosmetic concerns: adults with swallowing discomfort, neck pressure or a visible lump who do not want surgery. The ETA guideline recommends against treating asymptomatic nodules.
• Benign diagnosis first: the AAO-HNS Bulletin describes two benign biopsies, or one benign biopsy plus a clearly benign ultrasound appearance.
• Mostly cystic nodules: the ETA guideline prefers ethanol ablation before thermal ablation.
• Suspicious nodules: thermal ablation should never be performed on EU-TIRADS 5 (high-risk) nodules.

Results: volume reduction, symptoms, pain

The comparison is between two groups treated at the same hospital, not randomly assigned. Baseline volume difference P=0.004. Figures are taken from the abstract and figure legends of Thornton A et al., Endocrine 2026.

Note that the groups started from different points: MWA nodules were nearly twice as large at baseline (median 29.0 mL vs 16.6 mL). Volumes estimated after adjusting for baseline size also did not differ. Complications were low and similar, the most common being periprocedural pain. The authors conclude that "RFA and MWA achieved comparable volume reduction, symptom improvement, and complication rates."

How do RFA and MWA differ

Placing these results next to earlier studies shows the range of numbers. The table below uses the 12-month volume reduction and major complication data summarized in the ETA 2020 guideline.

Earlier figures are from Papini E et al., 2020 European Thyroid Association guideline (Eur Thyroid J 2020). Nodule sizes and definitions differ between studies, so the numbers cannot be compared directly.

In short, RFA has more randomized evidence and ranks higher in the guideline. MWA is often said to heat a larger area at once, but its evidence base is still weaker. The Columbia study adds one more piece of real-world North American data showing similar one-year results. The basics of RFA are explained on our RFA guide.

Where is it available and how is it approved

A billing code does not mean every insurer pays. Actual costs depend on the hospital and insurer.

Even in the US, the device used (RFA or MWA) and the specialty performing it vary between hospitals, so check in advance. When looking into treatment in Japan or elsewhere, first confirm whether the hospital offers it as standard care, a clinical trial or self-pay care.

Limitations and what patients should check

• Not randomized: doctors chose the method, so larger nodules clustered in the MWA group and selection bias is possible.
• Small MWA group: only 47 patients (60 nodules), so "no difference" does not prove the methods are equal.
• Loss to follow-up: according to the figure legend, 128 RFA and 12 MWA nodules were measured at 12 months, far fewer than at the start.
• One year only: the ETA guideline reports regrowth within 3 years in about 5–24%. This study cannot compare long-term regrowth.
• Disclosures: the senior author reported consulting for device companies (HistoSonics, Medtronic); the study reported no funding.

Questions to ask your doctor:

• How many biopsies were done on my nodule, and what confirms it is benign? Was calcitonin checked?
• Given the size and location of my nodule (distance from nerves and airway), would you use RFA or MWA, and why?
• How many of these procedures does this hospital perform, and what is its experience with complications such as voice change?
• Might I need more than one session, and what happens if it regrows? What is the ultrasound schedule after 3, 6 and 12 months?
• What are the pros and cons for me compared with surgery or observation?

To prepare for a consultation, see five questions to ask before RFA, and for reading study numbers, see how to check the study stage of overseas papers.

FAQ

Does RFA or microwave ablation shrink thyroid nodules more?

In this US study, the median 12-month volume reduction was 77.8% with RFA and 70.8% with MWA, with no significant difference at any time point. Because it was not randomized and only 47 patients had MWA, the practical approach is to choose with your doctor based on nodule size and location.

Will the nodule disappear completely?

Most nodules shrink rather than disappear. In this study, about 70–80% of the original volume was gone after one year, and the ETA guideline reports regrowth within 3 years in about 5–24%. Regular ultrasound follow-up is therefore needed.

What are the side effects of thyroid RFA?

The most common in this study was periprocedural pain (RFA 15.6%, MWA 12.8%). In the ETA guideline data, major complications of RFA were about 1.3–1.4%, and permanent voice change was 0.16% in a meta-analysis. Nodule rupture or bleeding is reported rarely.

Can thyroid cancer be treated with RFA?

This study and the ETA 2020 guideline cover benign nodules only. US societies consider RFA an option for low-risk papillary microcarcinoma under 1 cm in patients who prefer not to have surgery, but advise caution for larger cancers. Cancer needs separate evaluation.

This article summarizes published papers and public materials as general information, not medical advice. Discuss treatment choices with doctors who have examined the patient.