RF ablation may be effective in small renal tumors

August 1, 2006

Atlanta-Several groups have recently demonstrated the safety and efficacy of radiofrequency ablation in select patients ineligible for surgical excision of small renal tumors. Short-term data from these single-institution studies were presented at the AUA annual meeting here.

The first-line treatment for renal tumors is surgical excision. Increasingly, however, institutions are exploring probe ablative techniques for the treatment of small renal tumors in patients for whom excision is not a viable treatment option. These ablation techniques include cryoablation, usually performed laparoscopically under general anesthesia, and RF ablation, usually performed percutaneously under local anesthesia.

RF ablation is faster and less morbid than open or minimally invasive surgery, but does not allow complete histopathologic confirmation of tumor removal with negative surgical margins. For this reason, the technique is usually considered only for patients with co-morbidities that make them ineligible for surgical excision.

Patients were chosen for the Cleveland Clinic study if they had localized tumors no larger than 4 cm in diameter and were not recommended for surgical excision or laparoscopic cryoablation. Eighteen patients (21%) had a solitary kidney while 17 (20%) had a remnant kidney. This is in contrast to patients in the study who received cryoablation, in which only 21% of patients had a solitary kidney and 3% had a remnant kidney. For both ablation techniques, patients were followed with frequent magnetic resonance imaging and kidney biopsy at 6 months post-treatment.

"This is not a randomized study; these data must be viewed in that context," Dr. Hegarty told Urology Times.

"They [RF ablation and cryoablation] are less morbid and more convenient, but we don't have the security of knowing that the tumor has been removed. Long-term data are awaited given the indolent nature of most of these tumors," Dr. Hegarty later said at a media briefing held during the meeting. (Also see, "Biopsy advised to verify RF ablation efficacy in RCC," above.)

96% success rate

In another retrospective analysis of 26 patients with 48 tumors undergoing RF ablation between October 2000 and June 2005, a 96% success rate was achieved with no recurrences and only one patient with a persistent tumor (4%), researchers from the Mayo Clinic, Rochester, MN, reported.

All 26 patients in the study had a solitary kidney and were chosen for RF ablation based on co-morbidities, advanced age, multiple tumors, or prior nephrectomy. They were followed with computed tomography or MRI.

No post-procedural complications were reported and neither renal function nor blood pressure were affected by the procedure. One case of tract seeding, in which a tumor grows into the needle tract formed during the procedure, was reported for the one patient who had persistent tumor.

"RFA can be considered as a minimally invasive procedure for your high-risk patients," said lead author Amy Krambeck, MD, a urology resident working with Michael Blute, MD, and colleagues.