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

Halifax, Nova Scotia ( Small renal masses (SRMs) are a particularly worrisome condition that affects patients at a high volume worldwide and have actually increased in prevalence due to increases quality of imaging technologies. These tumors, usually less than 4 cm in diameter, are particularly daunting due to the possibility of them being renal cell carcinoma (RCC) and becoming metastatic. Typically, partial nephrectomy is the gold standard for the treatment of SRMs. However, an increase of radio frequency ablation (RFA) has emerged as a less invasive alternative to surgery.  Anil Kapoor, MD, a clinical urologist from McMaster University, described that overall survival, recurrence rates, and follow-up for this procedure have not been established. Therefore, his team set out to evaluate the time necessary to recur and rating of these recurrences when they appear. Additionally, they identified prognostic factors for tumor recurrence and incomplete ablation.

To test this, the researchers conducted a retrospective chart review of patients that underwent RFA for primary treatment for SRMs at their center between November 2007 and October 2017. The urologic team analyzed perioperative and baseline data including patient age, sex, pathology, maximum tumor size, PADUA score, and RENAL Nephrometry score (shown below). If patients had family history and oncocytoma was confirmed on biopsy, the patient would be excluded from the study. It is worth noting that repeat RFA at the ipsilateral kidney for recurrence or incomplete ablation was not considered a new procedure. Primary carriable measured was the time from initial ablation to recurrence. Incomplete ablations were defined as evidence of residual tumor at the original ablation site. 
Following the study‚Äôs completion, 84 patients were identified and included in the study. It was shown that 4.8% of patients experienced recurrences during the follow-up period with a median time of recurrence of 17 months. No recurrence was reported after 30 months. It was also shown that 6% of patients were identified with evidence of residual disease or incomplete ablation. After univariate analysis of perioperative factors, it was determined that there was no significant change in RENAL score or PADUA scores following treatment. However, tumor size was significantly associated with incomplete ablation or residual disease. 

Dr. Kapoor concluded by admitting the study was only a retrospective, single-center trial with a relatively small sample size and low event rate. In order for this to be more convincing study, a prospective, randomized controlled, multicenter trial must be conducted. However, Dr. Kapoor concluded that the risk of recurrence was very low in patients treated at his center with a large margin for success and no long-term recurrence past 30 months. 

Presented by: Anil Kapoor, MD, Department of Surgery, Division of Urology, McMaster University, Hamilton
Co-Authors: Cameron Lam1, Michael Nixon2, Nathan Wong1, Edward Matsumoto1
1Department of Surgery, Division of Urology, McMaster University, Hamilton, ON, Canada; 2Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada

Written by: Zachary Valley, MD, Twitter: @ZacharyAValley, Department of Urology, University of California-Irvine at the 73rd Canadian Urological Association Annual Meeting - June 23 - 26, 2018 - Halifax, Nova Scotia