Sword, fire, ice offer options in small renal masses

December 1, 2007

Nephron-sparing procedures now have clear advantages over radical nephrectomy for most small renal masses.

In addition to partial nephrectomy, radiofrequency (RF) ablation and cryoablation are showing good results, with even more treatments under development, Dr. Strup told attendees at the Urology Congress here. He classified the choice of procedures as "fire, ice, or sword."

Diagnoses of small renal masses-those less than 4 cm-are increasingly common, in part because of improved imaging techniques. Most renal cell carcinomas grow slowly- just 0.28 cm per year-and only 1% are metastatic, so observation is an option, particularly in patients whose life expectancy is short, Dr. Strup said. But patients often won't accept their cancer passively.

"We now know this is just as good an operation for the small mass as nephrectomy," he said.

Partial nephrectomy offers clear advantages when a patient has only one kidney, bilateral renal lesions, contralateral renal disease, or a systemic disease, such as diabetes, Dr. Strup noted. Laparoscopic partial nephrectomy offers better recovery than does open partial nephrectomy, but it is challenging.

"It's not cutting it out that's the problem; it's stopping the bleeding," he explained.

A new hand-assisted approach helps to avoid hilar clamping, but the hilum still should be clamped for deep or long resections, Dr. Strup said. A 1% to 2% hemorrhage rate and a 2% to 3% urinary leak rate are not unusual.

Dr. Strup believes that most surgeons with some laparoscopic experience can perform a laparoscopic partial nephrectomy, although he advises starting with radical nephrectomy, seeking experienced help, and finding a mentor. In fact, he thinks the laparoscopic partial nephrectomy will become the standard of care unless ablative technology replaces it.

From sword to fire

In RF ablation ("fire"), a high-frequency alternating current in the radiowave spectrum is transmitted to tissues through an array needle, generating heat. The success of the approach depends on the current intensity, the distance from the radiofrequency electrode, and the duration of the application: too little heat, and the lesion won't be big enough; too much heat, and charring will increase impedance and limit the lesion size. Tissue should be heated to at least 45 degrees C.

RF ablation is suitable for renal masses of <3 cm and in high-risk patients, such as the elderly and those with comorbidities or renal insufficiency, bilateral and/or multiple tumors, or a solitary kidney. The tumor should be exophytic, and should not be next to the bowel, ureter, or central collecting system.

From fire to ice

The "ice" is renal cryoablation, in which small probes circulate liquid nitrogen or argon gas to freeze the mass and 0.5 cm beyond it. Cells are damaged when ice crystals form inside them. Lysis is achieved when they thaw; two cycles of freezing and thawing are best.

Cryoablation is suitable for approximately the same patients as is RF ablation, although it can be used to treat renal masses up to 4 cm in size. The criteria for the location of the mass are approximately the same as for RF ablation, and the procedure can be approached percutaneously, retroperitoneal laparoscopically, or trans-abdominal laparoscopically, depending on the location of the mass.

Which procedure is better? Dr. Strup cited a study comparing RF ablation in 410 patients to cryoablation in 206 patients (J Urol 2006; 176:1973-7). About 13% of the RF ablation patients suffered a recurrence versus 4% of the cryoablation patients.