Presentation Authors: Nicholas Pickersgill*, Joel Vetter, Eric Kim, Kefu Du, Ramakrishna Venkatesh, Sam Bhayani, Robert Figenshau, Saint Louis, MO
Introduction: Percutaneous cryoablation (PCA) has emerged as a promising alternative to extirpative management of renal tumors in selected patients, with a reduced risk of perioperative complications. Disease recurrence is thought to occur most commonly in the early post-operative period. However, long-term oncologic follow-up data is lacking. We reviewed our ten-year institutional experience with PCA for renal tumors and assessed predictors of treatment failure.
Methods: We examined our prospectively maintained database of patients who underwent renal PCA from March 2005 to December 2015 (n=308) at a single institution. Baseline patient and tumor variables were recorded, and post-operative clinically-obtained cross-sectional imaging was examined for evidence of persistent or recurrent disease. Kaplan-Meier estimated survival curves were generated for disease-free survival (DFS) and Cox proportional hazards analysis was performed to identify predictors of DFS.
Results: Mean patient age was 67.2+11 years, mean tumor size was 2.7+1.3 cm, and mean nephrometry score was 6.8+1.7. At mean follow-up of 38 months, disease progression (e.g. new lymphadenopathy or metastasis) and/or local recurrence was observed in 14.3% (44/308) of patients. Excluding patients with solitary kidneys or Von Hippel Lindau syndrome, disease progression and/or local recurrence was observed in 10.1% (27/241) of patients. Of those with local recurrence, 80.6% (25/31) underwent re-ablation. The Kaplan-Meier estimated DFS curve is displayed in Figure 1. An initial plateau in treatment failures occurs approximately 24 months following PCA, followed by an equal number of treatment failures between 24 to 60 months. Controlling for age, body-mass-index, comorbidity, and tumor location, tumor size and comorbidity with chronic obstructive pulmonary disease (COPD) were significant predictors of treatment failure (HR 1.33 per 1 cm increase in size, p=0.001; HR 3.04, p=0.02, respectively).
Conclusions: In our ten-year institutional experience with PCA for the management of renal tumors, treatment failure occurs in approximately 10% of cases. Of these, roughly half occur beyond 24 months post-operatively. Increasing tumor size and comorbidity with COPD are both significant predictors of treatment failure.