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Kidney Tumors Destroyed Through Minimally Invasive Cryoablation: Presented at AUA

By Ed Susman

SAN FRANCISCO, CA -- May 13, 2004 -- Doctor said here May 12^th that cryoablation therapy can successfully destroy kidney tumors through use of a cryoprobe that is guided by magnetic resonance imaging.

"Percutaneous cryoablation of renal tumors is a minimally invasive surgery with low morbidity and high success rate," said W. Bruce Singleton, MD, Assistant Professor of Urology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, in a poster presentation at the 2004 American Urological Association Annual Meeting.

Dr. Shingleton and colleagues reported on their first 100 patients who were treated for renal tumors during the past 4 years. He said that the most important lesson they learned on the use of cryoablation in this disease is careful patient selection.

"The procedure is suited ideally to small tumors, exophytic, and in a location that can be accessed percutaneously," he said.

Most patients who undergo the cryoablation procedure receive general anesthesia, although the operation can be performed with intravenous sedation. The patient lies prone in the imaging unit and a biopsy of the renal mass is performed with an 18-gauge biopsy gun. The cryoprobe is placed into the tumor under imaging guidance and then the freeze process is initiated and monitored with repeat imaging. The freeze continues until the outer borders of the ice ball extend 5-10 mm beyond the edge of the tumor. The ice ball is then thawed using active heating. A second freeze cycle is then initiated after which the probe is removed.

"Careful follow-up with serial radiographic imaging after treatment is important for detecting evidence of recurrence of disease," he explained. "Continued monitoring will be necessary to ensure the durability of these results."

He places his patient on a follow-up algorithm that requires either a magnetic resonance imaging study or a computer-assistant tomography scan 1 month after cryoablation, serum creatinine monitoring and physical examinations at 3 and 6 months.

"The treatment is considered a success," he said, "when there is no evidence of contrast enhancement on subsequent imaging in the area where the tumor was situated."

Dr. Shingleton said 100 patients were treated with cryoablation at his institution. The average age of the patients was 63.9 years and 84 of the patients were men. The mean diameter of the lesion was 2.3 cm, although the tumors ranged in size from 1 cm to 7 cm.

Among these patients, 86% of the masses were destroyed after the first treatment. In the case of the 14 tumors that were not destroyed initially, a second procedure resulted in an additional 7 masses being frozen, giving an overall success rate of 93%.

He said that the initial cause of failure in 2 cases was the size of the lesion; the location was the problem in 11 cases; the reason for failure in the other case was not known.

Eleven patients had adverse events, 1 of these -- a perinephric hemorrhage -- was judged to be a serious event.

"Percutaneous cryotherapy is a treatment which has minimal associated morbidity with rapid patient recovery," Dr. Shingleton said.


[Presentation title: "Percutaneous Renal Tumor Cryoablation: Results in the First 90 Patients." Abstract #1751]

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