TAMPA, Fla.—Cryoablation guided by magnetic resonance (MR) imaging is safe and effective for treating solid renal tumors, even those up to 7 cm in diameter, according to new data presented here at the Society of Interventional Radiology annual meeting. The technique could be an alternative to partial or total surgical resection.

At the University of Mississippi, researchers looked at the outcomes of 71 patients treated with a total of 89 percutaneous cryotherapies. The mean age of the patients at initial cryoablation was 64.2 years. The group included 55 men and 16 women and they all had a dominant renal tumor. Patients were excluded from the study if they had a recent myocardial infarction (MI), experienced recent symptoms of angina, or had ischemic changes on electrocardiogram.

The study population had 72 masses (one patient had both left and right renal masses), all of which were either biopsy-proven malignancies or were suspicious for malignancy on computed tomography or MR scans. The renal tumors had a mean diameter of 3.1 cm (range 0.8 to 7.0 cm).

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The interventionalists ablated all 72 lesions with one to five needle-like cryoprobes. They used real-time MR imaging to monitor progression of the “ice ball” during the procedure. Tumors were considered successfully ablated if the ice ball extended 5 mm beyond the tumor margin.

The researchers successfully ablated 71 tumors. One patient was unable to undergo general anesthesia and requested early termination of the procedure due to physical discomfort. In this patient, 80% of the tumor was ablated.

Overall, 55 tumors (76%) required only a single treatment session and 16 (22%) required two treatment sessions. Subjects had a mean follow-up of 1.76 years (range one month to four years).

“We had pretty impressive results,” said lead investigator Bhavika Dave, MD, Assistant Professor of Radiology at the University of Mississippi Medical Center in Ridgeland. “And I think these are findings that should be of interest to nephrologists and urologists.”

Dr. Dave, who presented study findings, said there were only three documented post-procedure complications among the 89 cryoablations. Two patients had significant gross hematuria and one had a retroperitoneal hemorrhage requiring hospital admission and a blood transfusion. The three patients experienced no long-term sequelae.

“We found there were really few complications, and we were happy with what we saw,” said Dr. Dave in an interview with Renal & Urology News. “Many of the urologists [we work with] are comfortable with cryotherapy, and with the larger tumors, it looks like cryotherapy is better than radiofrequency ablation.”

Partial nephrectomy is recommended for renal tumors smaller than 3 cm in diameter. Cryoablation has been found to be successful in treating renal tumors up to 7 cm in diameter.

MR-guided cryoablation is performed without any radiation and results in less damage to surrounding normal structures, including renal parenchyma, ureters, and blood vessels. The new findings correlate well with other reported series, but more long-term follow-up studies are needed to prove efficacy with this treatment, she said.