Renal Cryoablation Outcomes Durable

NEW ORLEANS—Percutaneous renal cryoablation is associated with durable oncologic outcomes and may represent an effective, minimally-invasive treatment option for small renal tumors, according to a new study presented at the Society of Interventional Radiology's 38th Annual Scientific Meeting.

The single-institution study included 33 men and 17 women with small renal tumors. The study population was 78% Caucasian and 22% African American. The researchers evaluated tumors by size and location (exophytic, mixed, or central). The patients had a mean tumor diameter of 2.7 cm (range 1.1-4.9 cm). Among these tumors, 28 masses (54%) were exophytic, 21 (40%) were mixed, and three (6%) were central. Clinical success was defined as the absence of previously identified contrast enhancement.

Under computed tomography guidance, 52 masses were treated using 2-5 cryoprobes. The median follow-up was 36 months (range 12-57 months). Clinical success was achieved in 51 cases (98%). One patient experienced local recurrence after 13 months and underwent salvage cryoablation. This same patient developed a distant metastasis after an additional 34 months.

“Our progression-free metastasis and metastasis-free survival were both 98%. One patient died of a secondary malignancy. So, overall survival was 98%, as well,” said researcher Daniel B. Brown, Professor of Radiology and Director of Interventional Radiology at the Kimmel Cancer Center, Thomas Jefferson University, Philadelphia.

Dr. Brown noted that he and his colleagues excluded patients with less than one year of follow-up because local progression in these patients is most common at around 11 months.

Most published series evaluating the oncologic efficacy of renal mass cryoablation are limited by the inclusion of patients with follow-up of less than 12 months, he said. Renal cell carcinoma (RCC) has relatively slow growth kinetics, so clinical success may have been overestimated in earlier trials. The short-term efficacy of percutaneous renal cryoablation has been established, he said, so the focus needs to shift to durable tumor eradication.

 “The need for more mid-term data and for longer-term data is demonstrated by the single episode of recurrence in this series,” Dr. Brown told Renal & Urology News. “This patient essentially had two recurrences at separate sites, 13 and 47 months post-procedure. Those times points are both beyond the usual short-term follow-up period and would have appeared as a short-term success.”

In this current study, the average glomerular filtration rate decreased by 2.2% after the procedure. No patient experienced chronic kidney disease stage 4 or started dialysis. Biopsies were performed in 34 of the 50 patients. Biopsies were deferred in 12 patients with history of RCC in the contralateral kidney or locally progressive lesions after laparoscopic partial nephrectomy. Biopsies were not performed in four patients for technical reasons. Five complications occurred (10%), of which three were Clavien-Dindo type I (perinephric hematomas that responded to conservative therapy). A perinephric hematoma requiring a blood transfusion developed in one patient, but further management was unremarkable (type II) and 1 patient developed an asymptomatic pseudoaneurysm at the cryoablation site (type IIIa) and it was successfully treated with embolization.

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