Renal tumor ablation: energy-based technologies.

Abstract

Radical nephrectomy has been the standard of care for renal cell carcinoma since its description by Robson [44]. Within the past decade, partial nephrectomy has become established as an oncologically viable nephron-sparing alternative in select patients with a kidney tumor in the setting of actual or potential compromise of global nephron mass [40] or patients with a small (4 cm) tumor with a normal contralateral kidney [30]. However, although both procedures achieve excellent local cancer control, they are associated with considerable post-operative morbidity and prolonged recovery. Recent advances in urologic surgery have provided some attractive alternatives to open surgical radical or partial nephrectomy. Laparoscopic radical nephrectomy efficaciously retrieves an oncologically adequate surgical specimen while dramatically decreasing patient morbidity [23], and has been shown to be better tolerated in high-risk patients, including the obese [18] and the elderly [26]. As regards minimally invasive nephron-sparing procedures, laparoscopic partial nephrectomy has been performed in a few cases, although its technical refinement and standardization remain to be achieved. As an even less invasive alternative to laparoscopic partial nephrectomy, recent investigations have focused on the laparoscopic or percutaneous delivery of various energy forms in a realtime monitored manner, to achieve targeted destruction of renal parenchyma. Initial investigations into alternative treatments for solid organ tumors began with the prostate and the liver, due to the severe morbidity associated with surgery on the former, and the frequent unresectability of tumors in the latter. Subsequently, attention was turned towards the possible utility of these modalities with renal tumors. The unique anatomic location of the kidney allows it to be isolated easily during laparoscopic procedures. Furthermore, the kidney can be imaged well throughout any application. As a result, alternative ablative treatments for renal tumors have progressed from animal studies to clinical trials. Herein, we will discuss a variety of current alternative renal tumor ablation techniques: cryoablation (laparoscopic and percutaneous approaches), radiofrequency ablation (wet and dry), microwave thermotherapy, intracavitary photon radiation, and high intensity focused ultrasound (HIFU).