Radiofrequency Ablation for Papillary Thyroid Cancer: A Comprehensive Guide to a Minimally Invasive Treatment Option

Table of Contents

• Key Points
• Introduction: Understanding Papillary Thyroid Cancer
• What Is Radiofrequency Ablation and How Does It Work?
• The RFA Procedure: Step by Step
• How Doctors Evaluate RFA Success
• RFA for Small Thyroid Cancers (Papillary Thyroid Microcarcinoma)
• RFA for Multiple or Bilateral Tumors
• RFA for Larger Tumors (Over 1 cm)
• RFA for Recurrent or Metastatic Cancer
• Future Directions in RFA Research
• What This Review Could Not Prove
• Recommendations for Patients
• Frequently Asked Questions
• Source Information

Key Points

• RFA is a minimally invasive alternative to surgery for low-risk papillary thyroid microcarcinoma, with high tumor volume reduction and low recurrence rates.
• For single low-risk tumors 1 cm or smaller, studies report complete disappearance rates of 33.7%–100% and recurrence rates of 0%–4.5%.
• Compared with surgery, RFA causes fewer complications, shorter hospital stays, less bleeding, lower costs, and better postoperative quality of life.
• RFA is not recommended for aggressive subtypes such as tall cell, columnar cell, or hobnail variants; careful patient selection is essential.
• For recurrent tumors in the central neck, RFA is most effective when tumors have not yet invaded the trachea, and nerve injury has been reported in up to 12% of cases.

Introduction: Understanding Papillary Thyroid Cancer

Thyroid cancer is the most common cancer of the endocrine system—the network of glands that produce hormones regulating metabolism, growth, and countless bodily functions. Among all thyroid cancers, papillary thyroid carcinoma (PTC) accounts for approximately 80% of cases. The word "papillary" refers to the finger-like projections seen when the cancer cells are examined under a microscope.

Most PTC tumors grow slowly and behave in an "indolent" manner, meaning they tend not to spread aggressively. As a result, the overall prognosis for patients with PTC is generally excellent. However, the standard treatment has historically been surgery, and that brings its own set of challenges.

Surgery for PTC can lead to several complications, including permanent injury to the recurrent laryngeal nerve (the nerve that controls the vocal cords), hypoparathyroidism (underfunctioning of the parathyroid glands, which regulate calcium), visible scarring, and hypothyroidism (underactive thyroid) requiring lifelong thyroid hormone replacement therapy. These complications can persist for a lifetime and significantly reduce a patient's quality of life.

To avoid overtreating patients whose cancers would likely never cause harm, doctors have turned to active surveillance (AS)—a strategy of closely monitoring the cancer without immediate treatment. However, many patients find this approach stressful. Studies have shown that the decision to undergo delayed surgery during active surveillance is frequently driven by patient anxiety about the possibility of tumor growth and metastasis (spread to other parts of the body).

This is where radiofrequency ablation (RFA) enters the picture. RFA is a minimally invasive technique that destroys cancer cells using heat, guided by real-time ultrasound imaging. This review article, published in the journal Ultrasonography in March 2024, examines the current state of evidence for RFA in treating PTC, carefully analyzing its effectiveness, safety, and what the future may hold.

What Is Radiofrequency Ablation and How Does It Work?

RFA works on a straightforward principle: heat kills cancer cells. A specialized needle (called an electrode) is inserted directly into the tumor, and a high-frequency alternating current—between 200 and 1,200 kHz—is passed through it. This creates an oscillating (rapidly alternating) electric field around the needle tip.

Inside the tissue, this electrical field causes polar macromolecules (large molecules with positive and negative ends) and charged ions to vibrate at very high speeds. This rapid vibration generates frictional heat. Once the temperature in the tissue reaches 60°C (140°F), the affected cells undergo coagulation necrosis—a process where cells are irreversibly damaged, their proteins denature, and the tissue essentially "cooks." The dead tissue then shrinks in volume and is gradually absorbed by the body over time.

RFA is one of several thermal ablation technologies available, including microwave ablation, laser ablation, and high-intensity focused ultrasound. However, RFA has become the most widely adopted method for treating PTC, thanks to its proven track record and precision.

The RFA Procedure: Step by Step

Before undergoing RFA, patients typically go through a thorough evaluation. This includes:

• Ultrasound examination to assess the tumor's size, location, ultrasound characteristics, and blood supply (vascularity)
• Computed tomography (CT) scans of the neck and chest to check for lymph node involvement or distant metastases
• Fine-needle aspiration or core needle biopsy for cytopathological or histopathological analysis, including testing for the BRAFV600E gene mutation
• Laboratory tests to assess thyroid function and blood coagulation (clotting) ability

When it comes to the procedure itself, here is what patients can expect:

1. Positioning: The patient lies on their back (supine position) with the shoulders cushioned and the head tilted backward to fully expose the neck.
2. Ultrasound assessment: Multiple ultrasound sections are scanned to map the exact relationship between the tumor and nearby tissues.
3. Anesthesia: After routine disinfection, 1% lidocaine hydrochloride (a local anesthetic) is injected into the tissue under ultrasound guidance.
4. Protective fluid barrier: A liquid—either normal saline, 5% glucose, or lidocaine—is injected into the natural spaces around the thyroid gland. This creates a 5 to 10-millimeter protective zone that temporarily separates the tumor from critical structures like the trachea (windpipe), common carotid artery, and recurrent laryngeal nerve, shielding them from thermal injury.
5. Electrode placement: A safe puncture route is selected, and the electrode needle is positioned inside the tumor under real-time ultrasound guidance.
6. Ablation: For larger tumors, doctors use the moving-shot technique, which divides the tumor into multiple small ablation units and treats each one with edge-overlapping ablations, moving the heat source to protect nearby tissue. For small tumors, the electrode is inserted into the center and remains stationary throughout the procedure.
7. Monitoring: Throughout the ablation, heart rate, blood pressure, and oxygen saturation are closely monitored.

The duration of ablation, along with the power and energy settings, depends on the tumor's size and composition. For bipolar electrodes, power is typically set between 3 and 5 watts, while other RFA modalities may use up to 20 watts. After the procedure, contrast-enhanced ultrasound is performed immediately to assess the ablated area, which should extend 3 to 5 mm beyond the tumor edge to ensure a safe margin and confirm complete ablation. Patients are then monitored in the hospital for 1 to 2 hours, and any complications are evaluated based on clinical signs and symptoms.

The procedure differs slightly depending on whether the target is a primary tumor or a recurrent/metastatic lymph node:

• For primary PTC: Doctors typically use the trans-isthmic approach (entering through the narrow bridge of thyroid tissue connecting the two lobes). This allows stable electrode positioning, monitoring of the active tip's proximity to the recurrent laryngeal nerve, and prevention of heated material leaking into the area around the thyroid. The goal is a safe margin of greater than 3 mm.
• For lymph nodes: The needle path is chosen based on the node's location, the protective fluid barrier is formed around the lymph node itself, and a fixed ablation technique is generally used since these lesions are typically smaller.

How Doctors Evaluate RFA Success

Researchers evaluate RFA effectiveness using specific endpoints. The primary endpoint is the disease progression rate, which encompasses local recurrence (tumor returning at the same site), development of new tumors, lymph node metastasis, distant metastasis, or death due to PTC. The secondary endpoints include changes in tumor size and volume, tumor disappearance, technical success, procedure duration, hospital stay length, hospitalization costs, and postoperative quality of life.

Technical success is defined as the complete absence of enhancement on contrast-enhanced ultrasound at the conclusion of the procedure—meaning no blood flow is detected in the ablated region, indicating the tumor tissue has been destroyed.

Safety is assessed by tracking complications. Serious complications include thermal injury to surrounding structures (major vessels, esophagus, trachea, brachial plexus, or sympathetic chain), significant hematoma formation (collections of blood outside blood vessels), and hemorrhage. The most frequent complications are a sensation of heat during the procedure and pain or discomfort during or after treatment. Vocal changes due to thermal injury to the recurrent laryngeal nerve are another common and clinically significant complication that doctors watch for carefully.

RFA for Small Thyroid Cancers (Papillary Thyroid Microcarcinoma)

Papillary thyroid microcarcinoma (PTMC) is defined as a PTC tumor measuring 10 mm (1 cm) or less in diameter. The use of ultrasound-guided RFA for thyroid cancer was first reported by Dupuy et al. in 2001. Since then, more than two decades of research have produced numerous high-quality studies with large patient groups and extended follow-up periods.

A recent review of the literature reported that RFA for low-risk PTMC yields:

• Tumor volume reduction rates of 98.5% to 100%
• Complete disappearance rates ranging from 33.7% to 100%
• Tumor progression or recurrence rates between 0% and 4.5%

Two systematic reviews and meta-analyses, as well as a large-scale matching study, found no significant differences in postoperative outcomes between RFA and surgery for single low-risk PTMC. These outcomes included local tumor progression, lymph node metastasis, salvage surgery (surgery performed after another treatment has failed), and recurrence-free survival. However, the rate of complications was significantly higher after surgery than after RFA.

Furthermore, RFA proved significantly superior to surgery in terms of hospitalization costs, length of hospital stay, procedure duration, volume of bleeding, and postoperative quality of life. Importantly, RFA does not negatively impact subsequent surgical treatments if they become necessary later.

The table below summarizes key studies on RFA for single low-risk PTMC:

These studies confirm that RFA is a safe and effective treatment for single low-risk PTMC—cases without evidence of extrathyroidal extension (spread beyond the thyroid), lymph node metastasis, distant metastasis, or aggressive histological subtypes. Compared with surgery, RFA may offer a more cost-effective alternative for patients with PTMC who cannot or choose not to undergo surgery or active surveillance.

RFA for Multiple or Bilateral Tumors

Current guidelines only officially recommend thermal ablation for single low-risk PTMC. However, a growing body of research has examined whether RFA can also work for patients with multiple tumors or tumors in both lobes of the thyroid (bilateral disease).

Three studies from China have produced encouraging results:

While these results are promising, the sample sizes in these studies were relatively small. The authors emphasize that large-scale research with long-term follow-up periods is still needed to confirm the safety and effectiveness of RFA for bilateral and multifocal PTMC.

RFA for Larger Tumors (Over 1 cm)

For patients with larger PTC tumors that have not spread to lymph nodes—specifically those classified as T1bN0M0 (tumors larger than 1 cm but not exceeding 2 cm, with no lymph node involvement or distant metastasis) or T2N0M0 (tumors larger than 2 cm but not exceeding 4 cm, with no spread)—the 2015 American Thyroid Association guidelines recommend lobectomy with isthmic resection (removing only the affected lobe and the connecting bridge of tissue) rather than total thyroidectomy. This shift in guidelines reflects a growing preference for conservative treatment.

Recent research indicates that RFA for these larger tumors may produce outcomes comparable to those seen in T1aN0M0 tumors (the smallest category, 1 cm or less). The authors suggest this could be because PTC generally behaves in an indolent manner, and T1a, T1b, and T2 tumors have similar prognoses. The key studies are summarized below:

Based on these findings, RFA may be a viable alternative treatment option for patients with larger PTCs who are not good candidates for surgery or who prefer to avoid it.

RFA for Recurrent or Metastatic Cancer

Studies show that between 10.0% and 30.0% of patients with highly differentiated thyroid cancer experience local recurrence (the cancer returning in the neck) or metastasis (spread to other areas) after surgical treatment. Reoperating on these patients is challenging because anatomical changes and fibrosis (scarring) from the initial surgery can make reoperation difficult and risky. For this reason, current guidelines advocate the use of thermal ablation for the radical (curative) or palliative (symptom-relieving) treatment of recurrent or metastatic PTC.

Curative Ablation for Locally Recurrent Thyroid Cancer

The European 2021 guidelines state that radical ablation is feasible when there are three or fewer recurrent PTC tumors in the neck, each with a diameter of less than 2 cm, and no distant metastasis. A meta-analysis evaluating RFA for locally recurrent and metastatic PTCs reported:

• Tumor volume reduction rate: 89.5% to 100%
• Complete disappearance rate: 68.8%
• Average of only 1.3 ablation sessions required

Kim et al. found no significant differences in 3-year recurrence-free survival rates between RFA and reoperation for locally recurrent PTCs smaller than 2 cm. A recent meta-analysis confirmed that thermal ablation is safe and effective for locally recurrent and metastatic PTCs. However, major complications, such as nerve injury, have been reported in up to 12% of cases, particularly when the recurrent tumors are located in the central neck region. The authors advise caution before proceeding with ablation of recurrent tumors in this area.

Monitoring the biochemical response after RFA is also critical. Serum thyroglobulin (Tg) levels—a protein produced by thyroid cells—are a sensitive marker for predicting recurrence and metastasis. Tg levels can serve as an effective indicator of whether ablation was successful. Doctors also account for anti-Tg antibodies, which can temporarily rise after surgery as part of the immune response and may cause underestimation of serum Tg levels in standard tests.

Palliative Ablation for Recurrent Thyroid Cancer

When recurrent metastatic thyroid cancer invades critical structures or causes cosmetic concerns, reducing tumor volume becomes essential to relieve symptoms and improve quality of life. The American Thyroid Association recommends several management strategies for these cases, including reoperation, active surveillance, iodine-131 therapy (for disease responsive to radioactive iodine), external beam radiation therapy, and other nonsurgical approaches. Palliative RFA is one such approach.

Chung et al. studied RFA for recurrent thyroid cancer in the central neck area after surgery, categorizing tumors by their spatial relationship to the trachea. Their findings were striking:

• Tumors without tracheal invasion had the highest complete disappearance rate at 85.0%
• The rate decreased progressively for tumors forming acute, right, and obtuse angles with the trachea
• The lowest rate was seen in cases of intraluminal tracheal infiltration (tumor growing into the windpipe's interior)

The study reported a relatively high total complication rate of 21.4%, likely due to the inclusion of tumors located close to critical neck structures. Nevertheless, no life-threatening complications or long-term sequelae occurred during the follow-up period. Because RFA effectiveness is inversely related to the extent of tracheal invasion, the authors advise early RFA treatment for recurrent tumors in the central neck region.

For especially challenging cases—including lesions protruding from the skin or those that have ruptured—ultrasound-guided RFA combined with iodine-125 seed implantation has proven effective. Zhai et al. found that this combination approach safely and effectively controlled local metastatic tumors while also improving patients' quality of life.

Future Directions in RFA Research

While multiple studies have confirmed the safety and effectiveness of RFA for PTC, the review's authors identify three key areas where additional research is needed.

Improving Detection of Occult Cervical Lymph Node Metastasis

Metastasis to cervical (neck) lymph nodes is common in PTC, but detecting small metastatic lymph nodes on ultrasound is challenging. Several clinical studies suggest that contrast-enhanced ultrasound may help. Xiao et al. found that the isoenhancement pattern on post-vascular contrast-enhanced ultrasound with perfluorobutane (a contrast agent) was effective in identifying small cervical lymph nodes (short axis diameter of 8 mm or less) suspected of containing PTC. Zhang et al. reported that contrast-enhanced ultrasound lymphography provided better diagnostic performance than conventional B-mode ultrasound, especially for lymph node metastases smaller than 1 cm and for central cervical lymph node metastases. This technology could represent a new approach for early detection of lymph node spread.

Accurately Assessing PTC Aggressiveness

PTC is not a single disease—it includes 13 histopathological subtypes. The most aggressive of these are the tall cell, columnar cell, and hobnail variants, which have unique clinical, pathological, and molecular characteristics. RFA is not recommended for these aggressive subtypes. Preoperative assessment of tumor aggressiveness is therefore essential for tailoring treatment appropriately.

The authors suggest that combining analysis of molecular markers—such as the BRAF, RAS, TERT promoter, RET, and TP53 genes, along with the fusion genes RET/PTC, PAX8/PPARG, and NTRK—with artificial intelligence may enable more accurate evaluation of PTC aggressiveness, prognosis, and recurrence risk in the future.

New Technologies for Minimally Invasive Therapy

The thyroid gland sits in a crowded anatomical neighborhood, surrounded by the carotid artery, trachea, esophagus, and nerves. This proximity increases the risk of thermal damage during RFA. One promising new approach is irreversible electroporation, which uses high-voltage direct current to create a strong electric field. This induces the formation of permanent nanoscale fissures (tiny holes) in the cell membrane, leading to apoptosis (programmed cell death) and tumor necrosis.

Unlike thermal ablation, irreversible electroporation does not generate heat, so it preserves tissues that lack cellular components, such as blood vessels and nerves. Clinical studies have already confirmed its usefulness for liver and pancreatic cancers, suggesting it may become a viable ablation option for thyroid cancer as well—potentially with fewer complications than surgery.

Additionally, researchers are working on improving ultrasound visualization, since ultrasound cannot penetrate bone tissue, which can compromise clear imaging of target lesions in some cases.

What This Review Could Not Prove

The authors acknowledge several important limitations. First, most large-scale studies on RFA for PTC have been conducted in Asia (primarily China and Korea), with relatively few investigations carried out in Western countries. This geographic concentration may affect how broadly the findings can be generalized to other populations.

Second, studies on bilateral and multifocal PTMC have relatively small sample sizes, and long-term follow-up data are still needed to confirm safety and effectiveness for these indications. Third, while RFA appears to be very effective for low-risk tumors, data on its use in more aggressive PTC subtypes remain limited, and it is explicitly not recommended for the most aggressive variants.

Finally, the review notes that major complications, particularly nerve injury, have been reported in up to 12% of cases when treating recurrent tumors in the central neck—a reminder that RFA is not entirely risk-free and patient selection matters greatly.

Recommendations for Patients

Based on the evidence presented in this review, here is what patients should know when discussing treatment options with their healthcare team:

• RFA is a proven option for low-risk PTC. For patients with single low-risk papillary thyroid microcarcinoma (tumors 1 cm or less) who are ineligible for or decline surgery and active surveillance, RFA offers tumor volume reduction rates of 98.5% to 100%, complete disappearance rates of 33.7% to 100%, and recurrence rates of only 0% to 4.5%.
• RFA is safer than surgery in key respects. It causes fewer complications, shorter hospital stays, less bleeding, lower costs, and better postoperative quality of life—and it does not rule out future surgery if needed.
• RFA is expanding to more complex cases. Emerging evidence supports its use for bilateral and multifocal tumors, larger tumors (up to T2N0M0), and recurrent or metastatic disease, though more research is needed for these indications.
• Not all PTCs are treatable with RFA. The most aggressive subtypes (tall cell, columnar cell, and hobnail variants) should not be treated with RFA. A thorough pre-treatment evaluation—including ultrasound, CT, biopsy, genetic testing for BRAFV600E, and laboratory tests—is essential.
• Early treatment of recurrent tumors matters. For recurrent cancer in the central neck, RFA is most effective when tumors have not yet invaded the trachea. Patients with recurrent disease should discuss RFA options promptly rather than waiting.

As with any medical decision, patients should have a multidisciplinary consultation whenever possible, involving surgeons, endocrinologists, radiologists, and other specialists to determine the most appropriate treatment plan for their individual situation.

Frequently Asked Questions

What is radiofrequency ablation (RFA) for papillary thyroid cancer?

RFA is a minimally invasive treatment that uses heat from high-frequency electrical current to destroy cancer cells without removing the thyroid gland. A needle electrode is placed into the tumor under ultrasound guidance, heating tissue above 60°C to cause cell death. It is an alternative to surgery or active surveillance for certain patients.

Who is a candidate for RFA of papillary thyroid cancer?

RFA is a proven option for single low-risk papillary thyroid microcarcinoma, meaning a tumor 1 cm or smaller with no spread beyond the thyroid or to lymph nodes. It is not recommended for aggressive subtypes such as tall cell, columnar cell, or hobnail variants. Patients must have a thorough evaluation before treatment.

What side effects or complications can occur with RFA?

The most frequent side effects are a sensation of heat and pain during or after treatment. Vocal changes from nerve injury can occur. Serious complications, such as injury to surrounding structures or significant bleeding, are possible but less common than with surgery. For recurrent tumors in the central neck, nerve injury has been reported in up to 12% of cases.

What happens during the RFA procedure?

You lie on your back with your neck exposed. After local anesthesia, doctors inject fluid around the thyroid to create a protective barrier for nearby structures. An electrode is placed into the tumor under ultrasound guidance. For larger tumors, multiple overlapping ablations are performed. Afterward, you are monitored for 1 to 2 hours.

Can RFA be used for larger thyroid cancers or multiple tumors?

Emerging evidence shows RFA may work for tumors larger than 1 cm and for multiple or bilateral tumors, but studies are smaller and less conclusive. For example, one study of T2N0M0 tumors found a 93.7% volume reduction. Larger tumors up to T2N0M0 have shown promising results, but more research is needed.

Does RFA prevent the need for future surgery if cancer recurs?

RFA does not negatively impact subsequent surgical treatments if they become necessary later. Studies show that RFA for low-risk papillary thyroid microcarcinoma has low recurrence rates, and if surgery is needed later, it can still be performed. However, RFA is not entirely risk-free and patient selection is important.

My doctor recommends surgery for papillary thyroid microcarcinoma, but I read about radiofrequency ablation (RFA). Should I get a second opinion before deciding between RFA and surgery?

For a single low-risk papillary thyroid microcarcinoma (1 cm or less), radiofrequency ablation (RFA) has shown tumor volume reduction rates of 98.5–100%, complete disappearance in 33.7–100% of cases, and recurrence of only 0–4.5%. RFA causes fewer complications than surgery, with shorter hospital stays, lower costs, and better post-treatment quality of life, and it does not prevent later surgery if needed. However, aggressive histologic subtypes should not be treated with RFA. A second opinion can clarify whether your tumor is truly low-risk and whether RFA, surgery, or active surveillance fits your situation. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

Original Article: "Ultrasound-guided radiofrequency ablation for the treatment of papillary thyroid carcinoma: a review of the current state and future perspectives"

Authors: Guo-zheng Zhao and Ming-bo Zhang

Publication: Ultrasonography 2024; 43:79-87 (https://doi.org/10.14366/usg.23091)

Affiliations: Department of Ultrasound, First Medical Center, Chinese PLA General Hospital, Beijing, China; Department of Ultrasound, Air Force Medical Center, Beijing, China

Received: May 15, 2023 | Revised: December 1, 2023 | Accepted: December 11, 2023

Keywords: Thyroid; Papillary carcinoma; Ultrasound; Radiofrequency ablation

Note: This patient-friendly article is based on peer-reviewed research published in an open-access medical journal. It is intended for educational purposes and does not constitute medical advice. Patients should consult their healthcare providers for guidance on their specific condition. The original article is distributed under the Creative Commons Attribution Non-Commercial License (CC BY-NC 4.0).