RFA vs. MWA: Best Treatment for Benign Thyroid Nodules

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Introduction

Radiofrequency ablation (RFA) and microwave ablation (MWA) are minimally invasive, thermal ablation (TA) techniques used to treat benign and malignant thyroid nodules. In both techniques, a needle inserted through the skin delivers electromagnetic energy over about 30 minutes to heat nodules and induce coagulative necrosis.1,2 A reduction in compressive, functional, and cosmetic symptoms is associated with shrinkage of the treated nodule over the next 1 to 12 months.3

While both techniques are safe and effective, RFA offers several potential advantages over MWA, particularly for physicians who are new to thyroid ablation:

  • Established safety and efficacy
  • Greater nodule size reduction
  • Fewer complications
  • More controlled heating
  • Easier learning curve
  • More cost-effective
  • Category I CPT code

Established Safety and Efficacy

RFA has been used in medicine since the 1950s,4-6 predating MWA by many decades.7 Thyroid RFA was first reported in the clinical literature of the 2000s,8-10 whereas thyroid MWA was only reported in the 2010s.11 Over the years, thyroid RFA produced a robust track record of safety and efficacy, based on prospective, randomized trials and large, multi-institutional studies with up to 10-year follow-up.2,12,13,14-16 Major national and international consensus statements on thyroid ablation focus on RFA as a principal modality for thyroid ablation1,-3,12,17-20 and, in some cases, recommending it as a first-line therapy for treatment of certain thyroid nodules.2,3 In contrast, the clinical data for thyroid MWA is presently more limited and of lower quality.2,12

Greater Nodule Size Reduction

Reducing nodule volume is central to reducing symptoms caused by benign thyroid nodules.3 Complete elimination of the nodule is a principal objective in the treatment of cancerous thyroid nodules, such as papillary thyroid microcarcinoma (PTMC) and recurrent thyroid cancer (RTC). Volume Reduction Ratio (VRR) is widely used to characterize the amount of volume reduction due to RFA or MWA relative to a nodule’s initial size.

Several published meta-analyses compare nodule volume reduction for RFA and MWA treatments of benign thyroid nodules in thousands of patients. These studies demonstrate that RFA reduces nodule volume more than MWA, with statistical significance 6-12 months after the ablation procedure.21-23 For example, in a 2025 meta-analysis of treatment of over 2500 nodules, RFA showed a significantly higher VRR (83.3%) than MWA (76.9%) at 12 months (p = 0.02).23

Similarly, in a meta-analysis that compared RFA and MWA treatment of papillary thyroid microcarcinoma (PTMC), RFA showed a higher mean volume reduction rate (RFA 99.3% vs. MWA 95.3%) and a higher rate of complete disappearance (RFA 65.2% vs. MWA 56.5%).24

RFA’s proven, consistent advantage in nodule size reduction makes it an attractive choice for new and experienced thyroid ablation practitioners.

Fewer Complications

Radiofrequency ablation of benign thyroid nodules is associated with a lower rate of complications, pain, and risk of hypothyroidism than surgery,25,26 but complications do occur. Limiting the risk of pain, hematoma, skin burn, voice change, thyroid malfunction, and other adverse effects are important goals in thyroid ablation.25

Microwave ablation has been associated with a higher rate of complications than radiofrequency ablation, perhaps due to poorer control of applied energy.2,12 Several comparative studies have demonstrated a lower rate of complications for RFA than MWA, though not necessarily with statistical significance. For example, a multi-center prospective study of benign nodule ablation in over 1200 patients found the rate of major complications to be 4.78% RFA vs. 6.63% MWA.27 A 2024 prospective RCT of benign thyroid nodule ablation found the most common complication to be voice change, with occurrence rates 1.3% RFA vs. 6.6% MWA.28 A single-center retrospective study reported the rate of transient voice change to be 2.8% RFA vs. 4% of MWA.29 Meta-analysis of PTMC treatment found RFA to have lower pooled proportions of overall and major complications than MWA (overall complications: 2.6% RFA vs. 5.1% MWA; major compilations: 0% RFA vs. 2.5% MWA).24

RFA’s superior safety profile makes it more patient and physician-friendly treatment option for thyroid nodules.

More Controlled Heating

Thermal ablation techniques aim to raise nodule temperatures at least into the range 60-100°C, which induces near-immediate coagulation of tissue. Temperatures substantially above 100 °C induce vaporization of tissue water and carbonization30. Control of the heating process is important in thyroid ablation, given the proximity of thyroid nodules to the esophagus, trachea, RLN, carotid artery, vagus nerve, cervical sympathetic ganglion, skin, and other vital structures in the neck.2,19 RFA offers several advantages over MWA in terms of control over tissue heating due to differing physics.

The maximum tissue temperature during RFA is limited to 100-110 °C because vaporization increases tissue impedance and intrinsically controls RF energy delivery. The impedance signal can also be monitored and used to further control the ablation process,31 either automatically or by audio-visual display to the physician. In contrast, tissue impedance does not affect microwave energy delivery. This being the case, the maximum tissue temperature during MWA can exceed 150 °C and the impedance signal is not used for ablation control.31

Several studies attribute RFA’s record of greater nodule volume reduction over time to the fact that RFA produces lower maximum tissue temperatures and thus less carbonization than MWA. Carbonization due to MWA’s high temperatures is thought to hinder nodule shrinkage after MWA.21,22 Higher tissue temperature and poorer control of applied heat energy may also explain MWA’s association with a higher risk of complications than RFA for thyroid ablation.2,12

Superior intrinsic and feedback-based control of tissue heating may underpin RFA’s superior safety and efficacy in thyroid ablation.

Easier Learning Curve

The overall complication rate for thyroid RFA is low, but greater experience tends to improve patient outcomes. Several clinical groups have formally studied the learning curve for thyroid RFA. Appropriate board certification and specialization; clinical experience with thyroid treatment, head and neck anatomy, ultrasound, and FNA biopsy; phantom training; performance of 20-30 procedures with initial proctoring have been proposed as criteria for achieving independence and competence in performance thyroid RFA.19

To date, the learning curve for thyroid MWA has not been formally studied, and less experience with thyroid MWA is associated as a potential reason for poorer outcomes relative to thyroid RFA.23,24 One systematic comparison of RFA and MWA outcomes showed that RFA produced greater nodule size reduction than MWA for clinicians with less than 10 years of experience in thyroid ablation. The authors concluded “RFA showed a higher VRR at 12 months and seems more suitable for less experienced investigators.”23

A more accessible and better understood learning curve, in combination with consistently superior clinical outcomes, make RFA a particularly attractive option for practitioners who are new to thyroid ablation.

More Cost Effective

Thermal ablation systems include two key types of devices: a disposable probe that is inserted into the thyroid, and a reusable generator that delivers energy to the probe. RFA probes are generally less expensive than MWA probes, and prices for RFA generators are generally equal to or less than those of MWA generators.2

Capital expenditures and operating expenses are important considerations when introducing new devices into a clinical practice. RFA’s price advantage may improve access to thermal ablation therapy in hospitals and private clinics.

Category I CPT Codes

As of January 2025, RFA is the only thyroid ablation technique that has a specific category I CPT in the United States.32

  • CPT 60660: Ablation of 1 or more thyroid nodule(s), one lobe or the isthmus, percutaneous, including imaging guidance radiofrequency.
  • CPT 60661: Ablation of 1 or more thyroid nodule(s), additional lobe, percutaneous, including imaging guidance, radiofrequency (list separately in addition to code for primary procedure).

Reimbursement is critical to the availability of a therapy in the USA. A category I CPT code helps support accessibility and reimbursement opportunities.

Why Cambridge Thyroid RFA?

Cambridge Interventional is the only US-based manufacturer of thyroid RFA devices. The Cambridge RFA system provides unique real-time audio and visual feedback, enhancing procedural control, safety, and efficacy in treating thyroid nodules.

We believe that our approach helps to ensure optimal outcomes for both new and experienced users, and that our technology is the most reliable option for those looking to integrate thyroid ablation into their practice.

Want to learn more about incorporating CRF Thyroid RFA into your practice? Schedule a discovery call today and take the first step toward offering safer, more effective thyroid nodule treatments.

References

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Disclaimer:

Indications for use: The CRF radiofrequency ablation system of Cambridge Interventional LLC (“Cambridge”) is intended for use in percutaneous, laparoscopic and intraoperative coagulation and ablation of tissue.

Disclaimer: Read the instructions for use (“IFU”) of all medical devices prior to use. Clinical results, costs, and financial/insurance coverage may vary and are not guaranteed. The information contained in the multimedia content that is posted on the Cambridge Interventional website or that references or links to this text (“Content”) is for general informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment; standards of medical care or training; or the instructions, indications, and contraindications for use of Cambridge Interventional devices or any other medical devices. All information is provided in good faith, however Cambridge makes no representation or warranty of any kind, express or implied regarding the accuracy, applicability, fitness, or completeness of this information; of opinions expressed; of third-party publications referenced or summarized; or of third-party services presented. Always seek the advice of your physician about a medical condition. Never disregard professional medical advice, or delay in seeking it, because of something you have read or seen in this Content.

Adverse events: Reported adverse events or complications for RF ablation or coagulation procedures include, but are not limited to, the following (the long-term risks of RF ablations have not been established): abscess, ARDS (acute respiratory distress syndrome), arrhythmia, ascites, atrial fibrillation, bile duct injury, bile leakage, biliary fistula, biloma, bleeding, bone degeneration, bone fracture, bronchial occlusion, bronchopleural fistula, burn, cardiac arrhythmia, cardiac ischemia, chest tube, coughing, death, delayed hemorrhage into ablated tissue, device failure, device fracture in patient, diaphragm injury, diarrhea, edema, electric shock, emphysema, fever, fistula, hematoma, hematuria, hemoglobinuria, hemoptysis, hemorrhage, hemothorax, hoarseness, hypertension, hyperthyroidism, hypoesthesia, hypotension, hypothyroidism, infection, kidney atrophy, liver failure, liver insufficiency, multiple sclerosis exacerbation, muscle burn, muscle contracture, nausea/vomiting, nerve injury, neuropathy, nodule rupture, organ damage, pain, paresthesia, perforated colon, perforation, peritonitis, pes equinus injury, pleural effusion, pneumonia, pneumothorax, renal failure, skin burn, tumor recurrence, tumor seeding, urinary fistula, urinary incontinence, urinary retention, urine leakage, vasovagal reaction, vessel injury, vocal cord palsy, voice change, wound discharge. RF ablation procedures are not recommended for pregnant patients. Potential risks to the patient and/or fetus have not been established. General clinical residual risks for surgical procedures include anesthesia reaction, bleeding, blood clots, death, infection, organ injury, pain, and necessity for more invasive surgery, including open surgery, if complications occur.