Radiofrequency Ablation Successful in Small Thyroid Cancers

Miriam E. Tucker

May 05, 2023

SEATTLE ― Radiofrequency ablation (RFA) appears safe and effective for the treatment of low-risk papillary thyroid microcarcinoma (PTMC), new data suggest.

RFA is increasingly gaining favor as a less-invasive alternative to surgery for patients with large, symptomatic, benign thyroid nodules in the United States and elsewhere and for the treatment of thyroid microcarcinomas in other countries, particularly South Korea and China.

Now, new findings from eight patients seen at the Mayo Clinic are the first to be reported for use of RFA for PTMC in the United States, Kharisa Rachmasari, MD, an endocrinology fellow at Mayo, said on May 4 at the American Association of Clinical Endocrinology (AACE) Annual Meeting 2023.

Papillary thyroid cancers of 10 mm or less are the most common thyroid cancers, and their incidence is rising. They are commonly discovered incidentally in the setting of increased cross-sectional imaging. These tiny cancers are typically indolent, and they are associated with an excellent prognosis. In the United States, standard management is either surveillance or surgery, whereas RFA has been used in Europe and Asia for more than a decade, Rachmasari said.

"There has been some hesitancy when it comes to cancer, because there's no guarantee that we can do it in such a clean way as is done with surgery, where you can actually confirm a negative margin in pathology. And the follow-up is easier as well. With RFA, the PTMC is still there, and you can only follow it with ultrasound, not biochemically with thyroglobulin or certain biomarkers," she told Medscape Medical News.

Nonetheless, for these eight patients who underwent the procedure at Mayo's ablation clinic, where interventional radiologists team up with endocrinologists, there were no serious adverse events, and no further interventions were required during 24 months of follow-up, she reported.

Asked to comment, session moderator Anupam Kotwal, MD, assistant professor in the Division of Diabetes, Endocrinology and Metabolism at the University of Nebraska, Omaha, told Medscape Medical News, "It's very novel. We talk about balancing the comorbidities that come from treatment of thyroid cancer, but at the same time we want to treat it appropriately.... And of course, there are patient factors. Some may prefer to have the cancer completely out, while others are okay with watching and are against any cuts in their neck. This comes as kind of a middle ground."

But, Kotwal added, "[Investigators] definitely need to do a bit more work, especially in the population that may be at higher risk of cancer spread, such as those with a family history of thyroid cancer. We still don't know how autoimmune disease influences cancer progression."

He said that if RFA is to be used for PTMC, "I think it has to be done at a center that specializes in multidisciplinary care of thyroid cancers where there are not only the experts in doing the RFA procedure but also surgical expertise, in case a complication does happen, like a vocal cord injury. Or if the cancer is growing, they can expedite getting the person that appropriate treatment."

An Alternative to Waiting vs Surgery?

The eight patients were seen at Mayo Clinic between July 2020 and February 2023. All had papillary thyroid carcinoma that was confirmed cytologically via fine-needle biopsy and single lesions without lymph node metastasis. All the patients had been offered RFA as an alternative to either surgery or active surveillance.

Seven patients were female, and one was male (mean age, 53 years). All were euthyroid at baseline, and two were receiving thyroid hormone therapy. The mean diameter of their nodules was 9.5 mm, and the mean volume was 0.3 mL.

For the first six patients, the procedure was conducted under general anesthesia; deep sedation was used for the next patient, and moderate sedation was used for the most recent. "As we learn more and gain more experience, patients nowadays have moderate sedation," she explained.

The active tip size was 10 mm for five patients and 7 mm with three. The radiofrequency power that was delivered ranged from 25 to 45 watts. The median ablation duration was 6 minutes and ranged from 2 to 14.5. "Patients usually stay in the suite about half an hour, so it's a quick procedure, and the patient can go home on the same day," Rachmasari said.

Following the procedure, the ablated area increased in size during the first 3–6 months because the ablation was applied beyond the cancer margins in an attempt to ensure a negative margin, as is done surgically. By 18 months, the ablated area had shrunk and resolved.

All patients remained euthyroid in 18–24 months' follow-up, none had any cervical adenopathy, and none required subsequent intervention.

No significant adverse events were observed during or after the RFA procedure. A few patients complained of erythema and soreness around the area of the procedure, but this resolved with over-the-counter analgesia.

Longer follow-up will be necessary to detect any recurrence, Rachmasari noted.

Kotwal pointed out that lack of reimbursement for RFA has contributed to the slow adoption of RFA overall for the treatment of thyroid nodules in the United States, but added, "I think that will change quickly, especially with more and more data coming out about large benign nodules.... I think at least from the benign nodule standpoint, with discussions happening at national meetings and societies, it should push the payers to cover."

Overall, he said, "If you have a complication or it affects quality of life, all of those things add to the cost. So if you can use a procedure early on to prevent increasing size of either the big nodule or reduce the size of a big nodule, or even a small cancer, and give that person months or years, even if they ultimately need surgery, I think that's still a benefit for their quality of life. But again, we have to take patient factors into account."

Rachmasari and Kotwal have disclosed no relevant financial relationships.

American Association of Clinical Endocrinology (AACE) Annual Meeting 2023: Presented May 4, 2023.

Miriam E. Tucker is a freelance journalist based in the Washington DC area. She is a regular contributor to Medscape, with other work appearing in the Washington Post, NPR's Shots blog, and Diabetes Forecast magazine. She is on Twitter @MiriamETucker.

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