Objectives. The increased incidental detection of small (less than 4 cm) renal tumors has stimulated investigations of minimally invasive therapies. Radiofrequency energy is a relatively new and evolving technology that has been used for a variety of experimental and clinical applications. We evaluate the efficacy of hypertonic interstitial saline-augmented radiofrequency therapy to ablate a malignant VX-2 tumor implanted in a rabbit kidney, as measured by the completeness of tumor destruction and progression to metastasis.

Methods. The VX-2 tumor was surgically implanted into the left lower pole parenchyma of 18 New Zealand white rabbit kidneys. Ten days after implantation, hypertonic interstitial saline-augmented radiofrequency ablation was performed (n = 12) using a radiofrequency therapy system (RFT, United States Surgical Corp.). A sham operation was performed on a control group (n = 6). Animals were humanely killed at 5, 10, and 15-day intervals, and the clinical response and effect of radiofrequency energy on the malignant renal tissue was assessed.

Results. No postoperative complications were encountered. The mean size of the implanted VX-2 tumor was 1.87 cm². Kidneys in the treated group exhibited marked destruction of tumor tissue. Histologic analysis revealed coagulative necrosis of both malignant and normal renal tissue in the treated group. Three rabbits (1 control, 2 treated) died of metastatic disease.

Conclusions. Coagulative necrosis of renal parenchyma and tumor tissue was clearly demonstrated after radiofrequency ablation using the RFT system. The aggressive growth pattern of the VX-2 tumor often resulted in progression to metastatic disease while precluding complete tumor ablation. Hypertonic saline-augmented radiofrequency ablation is a promising new technology for the management of small, locally confined, renal tumors and has the potential for use with a minimally invasive approach.