Miriam E Tucker

May 30, 2016

ORLANDO, Florida — Radiofrequency ablation (RFA) is a viable alternative to adrenalectomy in patients with adrenal tumors who aren't surgical candidates, a new case report and literature review suggest.

Here at the American Association of Clinical Endocrinologists 2016 Annual Meeting, Lima Lawrence, MD, a second-year internal medicine resident at the University of Illinois at Chicago-Advocate Christ Medical Center, Oak Lawn, Illinois, presented a case report from her institution and a summary of the literature on the use of percutaneous RFA to treat adrenal tumors.

"RFA is a safe and effective alternative to adrenalectomy in patients who are unable to tolerate adrenalectomy or want a less invasive option of treating adrenal tumors, either primary or metastatic to the adrenal gland. It has been used in the treatment of bone tumors and hepatic lesions but is relatively new in the treatment of adrenal tumors," Dr Lawrence told Medscape Medical News in an interview.

The procedure is performed by trained interventional radiologists in the inpatient or outpatient setting under local or general anesthesia, she explained.

Asked to comment, session moderator David C Lieb, MD, associate professor of internal medicine and associate program director of the endocrinology fellowship program at Eastern Virginia Medical School in Norfolk, said: "It's something that providers may not always think about....It's another option for managing patients with adrenal tumors, specifically with adrenal tumors that are secreting hormones."

However, he added, "Certainly if there is any concern for malignancy, the gold standard would be [surgical] resection."

RFA

Dr Lawrence explained that, during the procedure, a radiofrequency needle with an active tip is inserted and gradually advanced to the adrenal lesion under real-time computed-tomography (CT) guidance. Either a single-electrode probe or cluster electrodes with three probes in a triangular arrangement can be used.

The procedure works by using alternating electrical current to generate heat and induce thermal damage and tissue necrosis at temperatures of 50°C to 60°C in the area adjacent to the electrode tip.

Complete tumor necrosis is achieved with a treatment time of 8 to 10 minutes, or a shorter time interval with multiple treatments. Immediate postablation CT is performed to confirm the absence of contrast enhancement within the tumor.

Case Report

Dr Lawrence presented the case of the first patient to undergo RFA for an adrenal tumor at her institution, a 65-year-old woman with a history of comorbid conditions, including uncontrolled hypertension and type 2 diabetes, who was found to have a cortisol-secreting adrenal tumor causing adrenal Cushing's syndrome. The patient was scheduled for adrenalectomy, but intraoperative finding of peritoneal studding and hepatic lesions precluded her from undergoing the procedure.

The patient received 2 weeks of alpha- and beta-blockade before successful CT-guided RFA of the right adrenal mass. A 14-gauge radiofrequency probe was inserted under CT guidance with an ablation zone of 3.5 cm and track ablation.

She experienced no procedural complications or blood loss and only received medications for postoperative pain management before discharge after 23 hours of postoperative observation. She had improvement in the size and decreased attenuation of the adrenal lesion with "drastic clinical and biochemical improvement after the procedure," Dr Lawrence noted.

The Evidence

To date, there have been no randomized controlled trials comparing safety, efficacy, and survival benefits of adrenalectomy vs RFA, but there have been several retrospective analyses of the procedure in small numbers of patients showing resolution of abnormal labs and clinical symptoms, she explained.

The earliest of these, from 2003, was a study of RFA in 15 patients with primary or metastatic adrenocortical carcinomas (Cancer. 2003;97:554–560). Eight had no tumor growth in a mean follow-up of 10 months, and eight of 12 tumors measuring less than 5 cm at baseline showed complete loss of enhancement and reduction in size.

In another retrospective analysis of 13 patients with functional adrenal neoplasms who underwent RFA over 7 years, all had complete resolution of biochemical abnormalities and clinical symptoms at a mean follow-up of 21 months (Radiology. 2011;258:308–316).

More recently, a 2015 study followed nine patients with Conn's syndrome and two with Cushing's syndrome for 12 weeks postablation (J Vasc Interv Radiol. 2015;26:1459–1464). Eight of nine patients with Conn's syndrome had normal serum aldosterone levels, and all patients with Cushing's syndrome experienced normalization of serum and salivary cortisol levels. Significant decreases were also seen in systolic and mean blood pressure with reduction in the number of antihypertension medications.

Several studies have also shown benefit for RFA in adrenal metastases, although here the data are more variable.

In a retrospective evaluation of 16 patients with adrenal metastases, 13 showed no evidence of local progression over a mean follow-up of 14 months, while two out of three patients with primary functional adrenal neoplasms had resolution of clinical and biochemical abnormalities, and discontinuation of antihypertensives at a mean follow-up of 78 months (Eur J Radiol. 2012;81:1717–1723).

And in a 2014 retrospective analysis of RFA of 10 adrenal metastases over 9 years, one of 10 recurred at 7 months, with no recurrence in the remaining patients at a mean follow-up of 26.6 months (J Vasc Interv Radiol. 2014;25:593–598). No patients with metastatic disease localized to the adrenal ablation site experienced local tumor recurrence.

Another 2015 retrospective evaluation of unresectable adrenal metastases in 35 patients over 9 years showed that 94% of patients lost tumor enhancement after initial RFA treatment, with local tumor progression in eight of 35 patients at a mean follow-up of 30 months (Radiology. 2015;277:584–593). The presence of extra-adrenal tumors and age greater than 65 years indicated a poor prognosis.

And finally, a 2014 systematic literature review compared adrenalectomy vs stereotactic ablative body radiotherapy and percutaneous catheter ablation, including RFA, for the treatment of adrenal metastases (Cancer Treat Rev. 2014;40:838–846). The authors reviewed 45 papers and noted marked heterogeneity in outcome reporting, patient selection, and follow-up, with inconsistent reporting of treatment-related complications.

Those authors concluded that at the time there was insufficient evidence to determine the best local treatment modality for isolated adrenal metastases. They recommended adrenalectomy as a reasonable treatment in suitable patients, with stereotactic ablative body radiotherapy as a valid alternative in nonsurgical candidates. But, they didn't recommend percutaneous catheter ablation, including RFA, until more studies with long-term oncological outcomes become available.

Indeed, Dr Lawrence said, "We acknowledge that further studies are needed in larger groups of patients with long-term follow-up before it can replace adrenalectomy."

Dr Lieb noted that because RFA leaves open the possibility of tumor recurrence, follow-up is key.

"Surgery is still the gold standard, but in patients who can't have surgery, are elderly, or have multiple comorbid conditions that affect ability to survive a surgery, I think it makes a lot of sense."

Drs Lawrence and Lieb have reported no relevant financial relationships.

Endocr Pract. 2016;22 (Supp 2); Abstract 115

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