Treatment of renal tumors with radiofrequency ablation.
BACKGROUND
Radiofrequency (RF) energy has been investigated as a minimally invasive modality for ablating small renal tumors. Recent advances in the application of this technology have improved its safety and effectiveness.


METHODS
We describe the technology of RF application and review the current delivery systems as applied to renal tumor ablation. We also review relevant animal studies, which have revealed the natural history of ablated renal tissue. Finally, we examine recent human trials with an emphasis on longer-term follow-up, imaging, complications, and successful ablation according to tumor location within the kidney; i.e., central v peripheral.


RESULTS
Radiofrequency ablation can be performed safely in a minimally invasive fashion either percutaneously or laparoscopically. Energy delivery varies, and available systems include dry, wet, cooled-tip, and bipolar electrodes. Heat rise and subsequent charring in the tissue adjacent to the electrode is limited by temperature or impedance-based feedback systems. In animal studies, ablation results in complete cell kill, as judged by nicotinamide adenine dinucleotide diaphorase staining. Clinical trials with intermediate follow-up show excellent success rates. Tumors >3 cm and central tumors have a higher recurrence rate after RFA than smaller, more peripheral tumors.


CONCLUSIONS
The current literature suggests that RFA is a promising minimally invasive method of treating small renal tumors. Nevertheless, long-term follow-up is still required, and questions remain regarding the optimal delivery system, duration of ablation, and method of surveillance.
Wagner
Andrew A
AA
Department of Urology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA. awagne14@jhmi.edu
Solomon
Stephen B
SB
Su
Li-Ming
LM
D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D002986:Clinical Trials as Topic; D004195:Disease Models, Animal; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007680:Kidney Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects / Q000379:methods; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000453:epidemiology; D009392:Nephrectomy / Q000379:methods; D011817:Rabbits; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D015996:Survival Rate; D013552:Swine; D016896:Treatment Outcome