CUA 2018: Surveillance Post-Radio Frequency Ablation for Small Renal Masses: Recurrence and Follow-Up

Halifax, Nova Scotia ( The management of renal cell carcinoma (RCC) continues to evolve as we begin to develop a better understanding of its natural history. We now know that growth kinetics can vary significantly for renal masses, and those with slow growth kinetics can often be watched without losing the opportunity for cure. As such, there has been a shift from surgery (radical or partial nephrectomy for every renal mass) to more conservative options to help reduce morbidity, unnecessary treatment and to spare nephrons. Active surveillance for small renal masses has become more established and is now a front-line treatment option in many guidelines. Similarly, when masses are small but growing, an alternative to surgery is focal therapy – radiofrequency ablation (RFA) being one such energy source option. 

While partial nephrectomy is widely accepted as the standard of care nephron-sparing approach in the management of clinically localized RCC (>90% disease-specific survival), focal therapy options have begun emerging as an alternative management strategy. It should be noted that local recurrence are noted to be slightly higher in focal therapy approaches,  although overall survival, recurrence rates, and follow-up strategy after RFA has not yet been clearly established. 

In this study, the authors used their institutional experience with small renal masses (SRMs) treated with RFA to evaluate the time to recurrence and recurrence rates. As a retrospective series of patients between 2011 and 2017, they found 84 patients with a solitary SRM and no evidence of metastatic disease treated with RFA; patients with familial syndromes were excluded. Biopsy proven oncocytomas were excluded as well.

Interestingly, repeat RFAs of the ipsilateral kidney for incomplete ablation was not considered a new procedure. The primary outcome was time from initial ablation to recurrence. 

In terms of demographics, the average age was 68.6±10.6 years, 71% were male, average tumor size was 2.42 ±0.81 cm. It would appear that 25 did not have prior biopsy; however of the remaining, 40 were clear cell, 16 papillary and 3 chromophobe RCC.

Over a median follow-up of 41 months (~3.5 years), there was a total of 4 total recurrences (4.8%) post-RFA. Albeit, this is a relatively short follow-up for SRMs. In the 4 patients with recurrence, the median time to recurrence was 17 months; none of the recurrences occurred beyond 30 months. 

In terms of incomplete treatment or residual disease, 5 patients had a residual disease (6%) and were identified within the first eight months post-RFA. 

The only prognostic variable identified as a predictor of residual disease was tumor size (hazard ratio 2.402; p=0.047) on univariate analysis, but not on MV analysis – other variables in the model included RENAL nephrometry score, PADUA score, age, and sex. Hence, patients with larger renal masses were more likely to have residual disease. This is supported by other institutions, including ours – patients with masses greater than 3 cm need to understand that they have a higher chance of residual disease, and therefore may not warrant focal therapy. 

Based on these results, the authors suggest (but need to validate on further studies) that surveillance post RFA can begin to reduce intensity beyond 30 months (though Dr. Kapoor conservatively stated 5 years). Current protocols recommend lifelong follow-up with cross-sectional imaging – this may be unnecessary beyond 3-5 years, similar to post-partial nephrectomy surveillance protocol.

Presented by: Kapoor, Anil, MD, Chair, Genito-Urinary Oncology Program, McMaster University — Hamilton, Canada
Co-Authors: Cameron Lam1, Michael Nixon2, Nathan Wong1, Edward Matsumoto1, Anil Kapoor1.
Author Information: 
1. Department of Surgery, Division of Urology, McMaster University, Hamilton, ON, Canada
2. Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada

Written By: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto   Twitter: @tchandra_uromd at the 73rd Canadian Urological Association Annual Meeting - June 23 - 26, 2018 - Halifax, Nova Scotia