The use of cryoablation, rather than radiofrequency (RF) ablation for the treatment of small renal masses may be controversial for some urologists, but recent data support the superiority of cryoablation.
Dr. Landman is a consultant to, and receives research support from, Oncura and American Medical Systems, as well as research support from Endocare. Dr. Evans receives research support from AstraZeneca, and he is a member of the speakers bureau at Boehringer-Ingelheim.
"These are currently the only two clinically viable options for minimally invasive ablation of the small renal mass," Dr. Landman said. "I favor cryoablation only because active targeting is unique to that modality."
With active targeting, the ablation process is observed in real time. Ice ball formation can be visualized using ultrasound for laparoscopic applications and with magnetic resonance imaging and computed tomography for percutaneous applications. With these technologies, the surgeon can ensure that the ice ball extends beyond the tumor in every dimension. With RF ablation, the device is deployed, but the urologist cannot actively monitor or visualize the thermal spread or ensure that the device achieves the proper temperature to destroy the tumor.
Data published in 2005 evaluated the recurrence and complication rates using RF ablation versus cryoablation. In 277 patients treated with RF ablation, 13.9% reported complications and 7.9% had tumor recurrence at 10 months' follow-up (BJU Int 2005; 96:1224-9). In 326 patients treated with cryoablation, 10.6% reported complications and 4.6% had tumor recurrence during a 30.8-month follow-up.
Three-year data from a study at the Cleveland Clinic demonstrated 96% efficacy of cryoablation in small renal tumors, and 5-year data showed 93% efficacy (J Urol 2005; 173:1903-7). Most recently, researchers demonstrated 97% efficacy with cryoablation at 3 years in renal tumors (Curr Opin Urol 2007; 17:144-50).
It is important to note, however, that no long-term data are available for either cryoablation or RF ablation.
Tips for successful cryoablation
Dr. Landman recommended the following cryoablation techniques to optimize patient outcomes:
"By optimizing technique, we can ensure that patients will have good outcomes," Dr. Landman said. "Also, I believe that as the data mature, we'll find more favorable outcomes with cryoablation compared to RF ablation because of our ability to actively target the tumor."
Christopher P. Evans, MD, chair of the department of urology at the University of California Davis School of Medicine, said the two ablative therapies may be particularly beneficial in certain patient populations.
"While partial nephrectomy remains the standard of care for definitive long-term outcomes, minimally invasive treatments using cryoablation and RF ablation for small renal masses are appropriate therapy, especially for patients with renal insufficiency or who are at significant risk for surgical morbidity," Dr. Evans said.