Radiofrequency Ablation of Renal Cell Carcinoma: Part 2, Lessons Learned with Ablation of 100 Tumors

Abstract and Introduction
Abstract

Objective: The objective of our study was to review radiofrequency ablation of 100 renal tumors and lessons learned with respect to electrode approach, effects on collecting system, bowel proximity, and patterns of residual disease.
Materials And Methods: Over 6 years, 100 renal tumors in 85 patients underwent radiofrequency ablation. Images were reviewed to determine the following: effect of initial electrode approach at and parallel to the tumor-kidney interface; effect of collecting system proximity to the tumor and to the zone of ablation; bowel proximity to the tumor and strategies to protect bowel; patterns of residual disease; and approaches at subsequent sessions.
Results: The initial placement of the electrode at and parallel to the tumor-kidney interface did not result in significantly fewer overlapping ablations (p = 0.91) or a lower rate of residual disease (p = 0.86). Direct contiguity of tumor or zone of ablation to the collecting system did not increase the complication rate. However, obscuration of calyces by a central tumor was a significant predictor of collecting system hemorrhage necessitating treatment (p < 0.001) seen in three of nine tumors obscuring calyces. Clinically significant urine leaks were rare (1/100) and related to downstream obstruction. There were no bowel complications despite the fact that 27 of the tumors were within 1 cm of bowel. Protective strategies progressed from reliance on electrode positioning to hydrodissection. Residual patterns were predominantly nodules or crescents, and straight electrodes were commonly used to approach residual disease.
Conclusion: Initial electrode position at and parallel to the tumor-kidney interface does not result in less difficult or more successful ablations. Contiguity of tumor or zone of ablation to the collecting system does not increase the risk of complications, but obscuration of calyces does. Bowel complications are rare, and protection with hydrodissection is becoming more common. Residual tumor presents as nodules or crescents of persistent enhancement.
Introduction

Radiofrequency ablation is being used increasingly to treat patients with small renal masses who are not ideal candidates for surgery.[1-7] In part 1 of our two-article series Radiofrequency Ablation of Renal Cell Carcinoma,[8] we reported the clinical experience and follow-up of 100 renal cell carcinomas that underwent radiofrequency ablation. Several additional issues with respect to radiofrequency ablation of renal masses can be addressed on the basis of current experience. Here in part 2, we review lessons learned such as the effect of the angle of approach of the electrode to an exophytic mass and the effects of radiofrequency ablation on the collecting system based on tumor proximity and bowel proximity to tumor, considerations for bowel displacement, patterns of residual disease, and approach to repeat ablation.