In both of these studies, the targeted tumor was harvested either immediately or after a 5-7 day delay following radiofrequency ablation. Much to the dismay of the surgeons, residual tumor was noted in 73-100% of these patients. Similarly, the authors of this reviewed paper reported a less than sanguine experience in 2002 with percutaneous radiofrequency of renal lesions averaging 2.4 cm in size, noting a CT based failure rate of 27% within 6 months of therapy. Now these same authors note a 96% success rate among 24 patients with lesions averaging 2.3 cm in size, with an average follow-up of 1.1 years. What is the reason for this dramatic difference? The simple answer is, more power. The earlier technology used probes at 75-110 watts, whereas the newer cool tip arrangement operates at 200 watts. The combination of increased energy with the cool tip, means further spread of the higher energy current and greater and more complete cell kill. Of note, in this series, is the successful treatment of 5 anterior lesions. The only caveat is to be very careful with percutaneous radiofrequency ablation if the lesion is near the ureteropelvic junction. They reported one case in which a UPJ repair was needed after treatment; interestingly, the targeted lesion was harvested at the time of this repair and was noted to have no viable tumor remaining. As more and more serendipitous small renal lesions are detected by CT scan, ultrasound, and MRI, percutaneous needle therapy, either by radiofrequency or cryotherapy, will grow. I believe that the time for urologists to become facile with these techniques, both from an imaging and treatment standpoint is now.

J. Urol. 171: 1814-1818, May 2004