Echotherapy: A Future Option for Benign Thyroid Nodule Symptoms?

A single session of high-intensity focused ultrasound (HIFU) ablation of symptomatic but benign solid thyroid nodules "appeared efficacious and safe" compared with hemithyroidectomy, researchers say in a study published in the International Journal of Hyperthermia.

Compared with patients who had one of their thyroid lobes surgically removed, those who underwent HIFU ablation had a shorter hospital stay, no scar, and were less likely to have problems with voice pitch a month later. At 6 months, they had a mean nodule shrinkage of 51% as well as a greater improvement in symptoms and a lower prevalence of subclinical hypothyroidism than patients who had surgery.

"This study provides a strong argument for HIFU ablation as a treatment for symptomatic benign thyroid nodule," say Brian Hung-Hin Lang, FRACS, from Queen Mary Hospital and the University of Hong Kong, and colleagues in the paper.

Dr Lang, who performed all the procedures, used the EchoPulse (Theraclion) HIFU device, which has a CE Mark for use to ablate breast fibroadenomas and benign thyroid nodules, CEO of Theraclion, David Caumartin, told Medscape Medical News.

This was the first study to compare HIFU ablation with thyroidectomy, Mr Caumartin noted.

Dr Lang, who treats more than 10 patients a month with this technique, "firmly believes that this should be the first [procedure] to be recommended for benign pathology of the thyroid," Mr Caumartin added.

The company plans to do a phase 1 study to seek approval from the US Food and Drug Administration (FDA) to use the HIFU device to treat benign symptomatic thyroid nodules and excise cancerous ones, and it could be approved for these clinical applications in the United States in 2 to 3 years' time, he speculated.

Asked for his thoughts, Hossein Gharib, MD, of the Mayo Clinic College of Medicine, Rochester, Minnesota, and past president of both the American Association of Clinical Endocrinologists and the American Thyroid Association, told Medscape Medical News: "HIFU is a novel and effective treatment for nodular goiter, [and] as a noninvasive procedure it is potentially safer and more attractive" than either radiofrequency ablation or laser ablation.

However, "it is currently not available in any center in the US and only in a few clinics in Europe," Dr Gharib said in his email, and so "more studies are needed to validate its use, efficacy, and cost-effectiveness."

HIFU Ablation for Thyroid Nodules Not Well Studied

Although most benign thyroid nodules may require only surveillance, some become large and symptomatic.

Surgical resection is the main treatment for large benign thyroid nodules (> 4 cm) that cause local pressure symptoms such as intermittent choking on swallowing or feeling pressure when lying flat, but this carries the risk of complications (including voice-quality problems), requires general anesthesia, and is costly, Dr Lang and colleagues note.

Thus, there is growing interest in minimally invasive techniques such as percutaneous ethanol injection for recurrent, benign thyroid cysts and thermal ablation techniques such as laser ablation and radiofrequency ablation for solid or predominately solid nodules.

HIFU ablation is an emerging technique that uses focused ultrasound energy to induce thermal ablation within the nodule.

"Its major advantage over other thermal techniques is that it could induce a focused thermal destruction of tissue with temperatures of up to 85°C without needle puncture and skin penetration," they note.

However, HIFU ablation "has not been well described," they say, "and it is particularly unclear what the efficacy and safety of HIFU ablation are relative to the conventional treatment (ie, surgery)."

They therefore performed a retrospective analysis in patients with symptomatic benign thyroid nodules who were seen at their center in Hong Kong from August 2015 to April 2016.

They identified 43 patients who did not wish to have surgery and had HIFU ablation and compared them with 103 patients who had hemithyroidectomy using a cervical approach.

The patients who had HIFU were younger (mean age, 48 vs 51) and more likely to be female and had a smaller mean nodule diameter (3.6 cm vs 4.5 cm) and mean nodule volume (5 cm³ vs 10 cm³) than the surgical patients.

Following HIFU ablation, the nodule volume swelled in the first week, but from 1 month to 6 months, there was a progressive shrinkage.

"It appears that the volume reduction might be similar to those with laser ablation but slightly less than those with a single session of radiofrequency ablation," Dr Lang and colleagues write.

Neither group had hypothyroidism (serum FT4 < 12 pmol/L), but when it came to subclinical hypothyroidism, significantly fewer patients in the HIFU ablation group developed this, only 2.3%, compared with 20.4% of patients in the surgery group (P = .008).

Patients who had surgery stayed in the hospital overnight, whereas the HIFU ablation was an outpatient procedure. A single session of HIFU cost US $1923 compared with the $5385 cost of surgery.

The surgery group also had poorer voice quality at 1 month than the HIFU ablation group.

And the proportion of patients who reported a "significant improvement" in symptom score was also higher in the HIFU ablation group than in the surgery group (67% vs 39%, P = .009).

Two Promising Related Studies, One European Center's Experience

A second related, 12-month study led by Dr Lang that has also been published in the International Journal of Hyperthermia reports that among 72 patients with symptomatic benign thyroid nodules who had a single HIFU ablation, only one patient (who had had a previous lobectomy) developed hypothyroidism, but without any clinical manifestations.

In a third related study of patients with symptomatic benign thyroid nodules with the same lead author, published in Radiology, 22 patients who had HIFU ablation had significantly greater shrinkage in nodule volume and improved quality of life at 1 year compared with 22 patients who simply received active surveillance.

"For patients with benign thyroid nodules who are candidates for surgical resection but are reluctant to undergo thyroidectomy, HIFU ablation might be a better therapeutic option than active surveillance alone because of the significant shrinkage in nodule size, reduced pressure symptoms, and improved health-related quality of life" a year later, Dr Lang and colleagues write.

Most patients have reservations regarding thyroid surgeries, because of the risks and the requirement of general anesthesia, another expert, Dr Hüdayi Korkusuz, from the department for nuclear medicine at Frankfurt University Hospital, in Germany, told Medscape Medical News in an email.

However, thermal ablation is performed only with local anesthesia. Moreover, HIFU ablation, unlike the two other types of thermal ablation (laser and radiofrequency), does not require a skin incision, which also destroys healthy tissue.

Thus, many patients prefer this option, he said.

"We have treated more than 400 patients with thermal ablation, [of which] about 10% of them were treated with" echotherapy (HIFU ablation), and "the number of treatments with echotherapy is constantly increasing more than other local treatment options," Dr Korkusuz noted.

The authors of the three studies disclose that they have no relevant financial relationships.

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Int J Hyperthermia. Published online April 24, 2017: Abstract. Published online March 24, 2017: Abstract

Radiology. Published online April 18, 2017. Abstract

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