Presented by: Genesis G. Dolgetta BS
Sarasota Memorial Health Care System Research Institute

Introduction

In this study, we describe the 14-year follow-up of oncologic and renal function outcomes for a cohort of patients who underwent laparoscopic radiofrequency ablation (LRFA) of SERMs with real-time temperature monitoring of the ablation zone with non-conducting fiberoptic thermistors versus a cohort of patients who underwent partial nephrectomy (PN).  This study is unique due to the large size of the tumors, the length of the follow-up, and the use of RENAL nephrometry scoring for all tumors.

Materials

All patients undergoing LRFA or PN for SERM were prospectively entered into an IRB-approved database. Renal function was assessed at 3 months and annually thereafter. Changes in GFR were calculated using the Modification of Diet in Renal Disease formula. LRFA was performed with a Covidien Cooltip probe system using multiple probes and multi-pass technique. Direct real-time, fiberoptic temperature monitoring was performed for each case with temperature goals of greater than 60 degrees C achieved at the deep and peripheral margins. PN was performed with standard arterial and venous clamping and a sliding clip renorrhaphy closure technique.   Oncologic and renal function outcomes for both cohorts were compared using a propensity-score-based analysis with adjustment for age, baseline renal function, tumor volume, RENAL score, histologic stage, and grade.  

Results

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Patients undergoing LRFA were older (median age 73 vs. 68 years, p<0.001), with similar BMI (median 26.8 vs. 28.5), and gender (59% vs. 68% male, p=0.17) compared to PN. Median tumor volume was 17.2 for LRFA and 33.5 for PN (p<0.001), median pre-surgery GFR was 59.7 for LRFA vs. 49.9 for PN (p=0.002), and median RENAL score was 6.0 for LRFA vs. 9.0 for PN (p<0.001). LRFA had a higher % of T1a patients (72% vs. 38.5%, p<0.001).  With propensity score adjustment, patients undergoing PN had 92% lower risk of DSM (p=0.048), 98% lower odds of metastasis (p<0.001), 95% lower odds of radical nephrectomy (p=0.002), and 98% lower odds of overall salvage procedure (p<0.001). Overall mortality was not significantly different between the groups (HR=0.5, 95%CI 0.14-1.59, p=0.22).  Four percent of patients undergoing LRFA required salvage PN (3/75). Propensity adjusted mean % change in GFR at one year was significantly greater for PN vs. LRFA (21.6% vs. -11.6%, p=0.022). 

Conclusion

Although LRFA is feasible with overall excellent preservation of kidney function and 94% disease-specific survival, preservation of renal function and recurrence-free survival decline inversely with tumor size and RENAL nephrometry score. Local tumor bed recurrence, metastasis, and DSM occur more frequently with LRFA than PN over 14-year follow-up with these large tumors despite the independent temperature monitoring with LRFA.  

Funding

None.

Lead Authors

Tonya S. King, PhD
Sarasota Memorial Health Care System Research Institute

Robert I. Carey, MD, PhD
Sarasota Memorial Health Care System

Co-Authors

Benjamin J. Behers, MD
Florida State University College of Medicine

Maximilian S. Carey,
Sarasota Memorial Health Care System Research Institute

Karim Ghazli,
Sarasota Memorial Health Care System