Ethanol Ablation a Cheap Alternative for Small PTC Recurrence

Pam Harrison

September 25, 2012

September 25, 2012 (Quebec City, Quebec) — Ethanol ablation is a cheap and, in expert hands, harmless alternative to further neck exploration in patients with previously resected, low-risk papillary thyroid cancer (PTC) and a stage I recurrence in regional lymph nodes, according to a leading proponent of the procedure.

Ian Hay, MD, and colleagues from the Mayo Clinic in Rochester, Minnesota, report that in 83 patients with stage I recurrent PTC followed for an average of 5 years, 50% of ablated nodes disappeared from repeat sonograms typically after 2 ultrasound-guided percutaneous ethanol ablation 10-minute sessions.

All 124 ablated nodes in these 83 patients shrank in size and no regrowth has been observed, added Dr. Hay. None of the nodes adequately treated with ethanol ablation has required subsequent neck reexploration either.

Dr. Hay presented the study results here at the American Thyroid Association 82nd Annual Meeting.

"We started this ablative procedure 21 years ago," Dr. Hay told Medscape Medical News. "My great hope for this innovative procedure is in the bread and butter treatment of PTC, which is young patients with stage I node-positive disease. I think everybody would agree this is the most common reason patients with thyroid cancer go to see an endocrinologist nowadays."

Adequate Treatment

Despite adequate treatment at the time of diagnosis, about 10% to 20% of PTC patients develop recurrence in regional lymph nodes over time.

Among the traditional treatment options for neck nodal recurrences are neck dissection, radioiodine therapy, and external irradiation.

However, more than 2 decades ago, researchers at the Mayo Clinic developed ultrasound-guided percutaneous ethanol ablation, which is performed under local anesthetic. Using ultrasound guidance, a small volume of 95% ethanol is directly injected into the nodal metastases.

"Injections are usually repeated on the following day," Dr. Hay explained, "and after successful ablation, nodes progressively decrease in size until they become these tiny avascular remnants."

Since 1993, researchers at the Mayo Clinic have been selecting PTC patients for ablation if they have a biopsy-proven adenopathy and are poor surgical candidates or prefer not to have repeat neck surgery.

These patients are usually unresponsive to radioiodine therapy.

"In 2002, we described the outcome in 29 nodes treated in 14 patients and all nodes decreased in size at an average decrease of 96% at 2 years," Dr. Hay reported (AJR Am J Roentgenol. 2002;178:699-704).

The current study initially involved 149 patients who were selected for ethanol ablation from 1993 to 2012. This was subsequently narrowed down to 115 patients with localized disease only, and a total of 171 nodes were ablated.

In 88 of these stage I patients, who were a mean age of 37 years at ablation, "131 biopsy-proven nodes were selected for ethanol ablation," Dr. Hay said. "They were injected with a mean of 0.8 mL of 95% ethanol," he added.

A number of patients in this group were not reassessed, bringing the number of evaluable patients in this series to 83.

As Dr. Hay noted, adverse effects from the procedure include mild neck pain that lasts a few hours and is responsive to minimal analgesia.

In their 20-year experience, only 2 patients developed temporary hoarseness, Dr. Hay added.

At follow-up, 30% of ablated patients had an undetectable thyroglobulin level (below 0.1 ng/mL), a result investigators deemed to be ideal; 65% had a postablation thyroglobulin level below 2 ng/mL, which the investigators considered acceptable.

Postablation thyroglobulin levels during follow-up were suggestive of residual disease, and considered unacceptable, in only 4 patients (5%).

"Nodes beget nodes," Dr. Hay said; almost 1 in 4 of this group of stage I patients developed new metastases during follow-up.

"However, 80% were adequately treated with ablation alone and only 4 required repeat neck surgery," Dr. Hay said. "In total, ablation prevented these 83 patients from undergoing 99 potentially hazardous neck reexplorations, at an average cost of $1583 per ablation, which is in sharp contrast to the astonishing $35,000 to $45,000 it costs to reoperate."

Isolated Metastatic Deposit

Sylvia Asa, MD, PhD, from the University of Toronto in Ontario, Canada, told Medscape Medical News that ethanol ablation might have some value when patients have a very small isolated metastatic deposit in a tumor that was otherwise completely resected and where the risk of doing surgery might be too great for the patient.

"My concern with alcohol ablation is that, in the hands of people who don't know how to do it, it can have side effects and, more important, it can have detrimental effects when used inappropriately," she explained.

From a pathology perspective, for example, "we know that alcohol ablation can create significant tissue damage to the point where it can preclude us from being able to reach a diagnosis of what the lesion was to begin with," Dr. Asa said.

Ideally, the injected ethanol will be contained inside the lymph node, but if it migrates out into other tissue, "it can cause a lot of local reaction and fibrosis and other problems for the patient," she added.

The foci of metastatic disease that might respond to ethanol ablation have to be very small because if they are too big, alcohol will not kill the tumor.

"Dr. Hay was very clear that he was using ethanol ablation only in biopsy-proven metastatic disease from a known thyroid primary that has spread to very localized small disease," Dr. Asa concluded. "In that circumstance, I think [alcohol ablation] probably is a reasonable alternative to surgery."

Dr. Hay and Dr. Asa have disclosed no relevant financial relationships.

American Thyroid Association (ATA) 82nd Annual Meeting. Oral abstract 8. September 20, 2012.