Thermal Ablation Approaches Similar in Efficacy for Benign Nodules

Nancy A. Melville

October 18, 2018

WASHINGTON, DC — Three common approaches for noninvasive treatment of benign thyroid nodules with thermal ablation have similar efficacy and safety profiles in a comparison involving treatment of 200 nodules.

"This study's message is clear: thermal ablation for benign thyroid nodules is safer than surgery, with only a few transient side effects," said first author Adrien Ben Hamou, MD, of the Endocrinology Department at the University Hospital in Lille, France, who presented the findings here at the 2018 Annual Meeting of the American Thyroid Association (ATA).

"There is a learning curve and operators need training, but the final aim is to limit unnecessary surgeries."

Minimally invasive thermal ablation of small thyroid nodules is seen as a preferable alternative to thyroidectomy surgery, which often turns out to have been unnecessary. But few, if any, studies have compared the leading ablation methods — radiofrequency ablation (RFA), laser ablation (LA), and high-intensity focused ultrasound (HIFU).

Richard J. Wong, MD, chief of Head and Neck Service, Department of Surgery, Memorial Sloan Kettering Cancer Center in New York City, noted that this new study offers a unique comparison of the technologies.

"All three techniques have been described before, in mostly small retrospective reviews, but very few studies have compared them to one another," Wong, who comoderated the ATA session, told Medscape Medical News.

He added, however, that the multitude of factors involved in the delivery of thermal ablation of nodules can complicate comparisons.

Over 80% of Patients Had Reduction of Symptoms With All Methods

To compare the three methods, Ben Hamou and Herve Monpeyssen, MD, of the American Hospital of Paris, France, enrolled 176 patients presenting with thyroid nodules of benign cytology or histology who had initially been offered surgery for their nodules but had refused.

Of 200 thyroid nodules that were identified, the mean size was 16.8 ± 16.6 mL and 165 (82.5%) of the nodules were palpable. Among them, 99 (54%) were treated with RFA, 67 (40.5%) were treated with LA, and 10 (5.5%) were treated with HIFU. Most patients (80.7%) were women, and the mean age of participants was 51 years.

At the first 6-week follow-up, a comparison of RFA and LA showed nodule volume decreases from baseline were greater with RFA (from 20.4 mL to 10.7 mL; 51.5%) compared with LA (13.6 mL to 8.5 mL; 40.2%; P < .001). The differences in reductions between the two at the 12-month follow-up, though both large, were no longer significant (73.2% vs 74.3%).

No other differences were observed at 6, 12, or 18 months in terms of mean volume reductions between RFA and HIFU (66.5% vs 57.8%, respectively) or between LA and HIFU (68.1% vs 57.8%), after adjusting for factors including age, initial nodule volume, vascularization, and Thyroid Imaging Reporting and Data System (TI-RADS) score.

Pain complaints were comparable in the RFA and LA groups (57.6% vs 53%), but were more frequent in the HIFU group (80%).

On average, in terms of reductions of clinical symptoms, more than 80% of patients in the three groups reported disappearance of symptoms including discomfort (–72%), aesthetic inconvenience (–72%), dysphagia (–26%), and dysphonia (–4%).

There were six (3.4%) major adverse events reported, including two transient recurrent laryngeal nerve palsy cases in the RFA treatment group, one hematoma in the LA group, two abscesses that were successfully drained in the LA group, and one spontaneously regressive Horner's syndrome in the HIFU group.

Ben Hamou added that there was also one case of Graves disease and two other cases of hyperthyroidism in the RFA group, but there were no cases of hypothyroidism or hypoparathyroidism during the 18-month follow-up.

RFA Best for Larger Nodules, LA for Medium Ones, and HIFU for Small?

"After 18 months' follow-up, thermal ablation was efficient in reducing nodule size by 60% (HIFU) to 75% (RFA and LA), with no difference between techniques," Ben Hamou concluded.

He noted that a limitation includes the obviously small number of HIFU nodules. "Only a few nodules were treated with HIFU, representing the first treated nodules with HIFU in France and at our center," he told Medscape Medical News.

"In my opinion, RFA and LA are clearly more efficient, with no difference between these two techniques, except at 6 weeks (RFA had better results than LA)," he added.

"Of course, the use of one or another technique depends on the expertise of the clinician, the size of the nodule, the structure, and its location. However, no randomized series has been published yet."

In addition, the nodule characteristics can determine which method is most appropriate, Ben Hamou explained.

"Currently, RFA is considered more effective to treat large solid nodules (> 15 mL), whereas LA is considered more effective to treat medium cystic nodules (> 10 mL) but the results of studies comparing both treatments are discordant," he said.

"HIFU indications are still debated and it is mainly performed to treat smaller nodules (< 5 mL) inaccessible to other techniques or when patients refuse other mini-invasive techniques."

Surgery Is Still Recommended If Nodules Are Suspicious

Wong, session moderator, expanded on his comments regarding the factors that could affect outcomes.

"It was interesting to see no differences between the three [ablation] techniques, but there are many variables that may play a role in their efficacy. These include the energy level delivered and how aggressively the modality is used on the nodule — these are hard to control and make direct comparisons difficult."

And Wong agreed with the authors that the skill of the operator is also a key factor.

"These are tools that are operator dependent. Imagine a comparison of a surgical laser versus cautery versus blade and the outcome is how well a tumor is removed," he said. "All three could be equally good depending on the skill of the operating surgeon."

Importantly, Ben Hamou also stressed that, if nodules are suspicious, surgery is still recommended.

"We should be very clear about the indication and that these techniques should not deter the care of suspicious or malignant nodules. In these cases, we know that surgery is still the gold standard," he concluded.

The authors and Wong have reported no relevant financial relationships.

2018 Annual Meeting of the American Thyroid Association. October 5, 2018; Washington, DC. Abstract Clinical Oral 33

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