Small renal tumors: natural history, observation strategies and emerging modalities of energy based tumor ablation.

With further advances in the technology of non-invasive imaging modalities as well as their utilization, diagnosis of incidental renal tumors has increased considerably. A large proportion of these renal tumors have been small (<4 cm) masses, for which nephron sparing surgery has been proven to be effective for. The trend toward minimally invasive options in the management of renal tumors has prompted interest in energy-based ablation techniques as a possible alternative to radical or partial nephrectomy in select patients. This article will review the natural history of small renal neoplasms and the emerging modalities of energy based energy ablation such as cryoablation, radiofrequency ablation, interstitial photon radiation, interstitial laser technology, microwave ablation, and Cyberknife extracorporeal renal tissue ablation.