Radiofrequency Ablation of Renal Cell Carcinoma: Part 1, Indications, Results, and Role in Patient Management Over a 6-Year Period and Ablation of 100

Abstract and Introduction
Abstract

Objective: The objectives of our article are to review our experience with radiofrequency ablation of renal cell carcinoma and to assess size and location as predictors of the ability to achieve complete necrosis by imaging criteria.
Materials and Methods: Over a 6-year period, 100 renal tumors in 85 patients underwent radiofrequency ablation at a single institution. The absence of enhancement on CT or MRI after radiofrequency ablation was interpreted as complete coagulation necrosis. Results were analyzed by tumor size and location using multivariate analysis. A p value of 0.05 or less was considered significant.
Results: All 52 small (3 cm) and all 68 exophytic tumors underwent complete necrosis regardless of size, although many large tumors (> 3 cm) required a second ablation session. Using multivariate analysis, we found that both small size (p < 0.0001) and noncentral location (p = 0.0049) proved to be independent predictors of complete necrosis after a single ablation session. Location was a significant predictor (p = 0.015) of complete necrosis after any number of sessions, whereas size showed a strong trend (p = 0.059) toward predicting success after any number of sessions. Complications were either self-limited or readily treated and included hemorrhage (major, n = 2; minor, n = 3), inflammatory track mass (n = 1), transient lumbar plexus pain (n = 2), ureteral injury (n = 2), and skin burns (n = 1).
Conclusion: Radiofrequency ablation is a promising minimally invasive therapy for renal cell carcinoma in patients who are not good operative candidates. Small size and noncentral location are favorable tumor characteristics, although large tumors can sometimes be successfully treated with multiple ablation sessions.
Introduction

The incidence of renal cell carcinoma is increasing, with most renal cell carcinomas now being detected as incidental imaging findings.[1-3] The desire to preserve renal function in patients with comorbid conditions or with multiple renal cell carcinomas has been the impetus for the development of minimally invasive therapies such as partial nephrectomy and laparoscopic nephrectomy.[4,5] The newest of these minimally invasive therapies are the ablative therapies such as radiofrequency ablation and cryoablation.[6,7] As determined by imaging criteria, the short-term effectiveness of percutaneous imaging-guided radiofrequency ablation in treating small renal cell carcinoma has been shown and validated in several early studies over the past 5 years.[6,8-15]

As new therapies are introduced, 5-year results are compared with those for conventional open nephrectomy. Although the literature currently contains several series of small renal cell carcinomas treated with percutaneous radiofrequency ablation, all these series report mean low follow-up periods of less than 2 years.[8-15] Thus, 5-year results of substantial cohorts of patients are awaited. Nevertheless, several issues with respect to performance of radiofrequency ablation of renal masses can be addressed on the basis of current experience. We undertook these studies to review our experience with radiofrequency ablation of 100 renal masses. In this article, part 1, we review indications, technique, results based on size and location, clinical and imaging follow-up, and complications. In part 2, we review technical considerations such as patterns of residual disease and approach to ablation of residual disease, effects on the collecting system, considerations for bowel displacement, and angle of approach of the electrode relative to the mass.