Arterial Clamping Increases Central Renal Cryoablation Efficacy: An Animal Study.

INTRODUCTION: The minimally invasive treatment of small renal masses with cryoablation has become increasingly widespread during the past 15 years. Studies with long-term follow-up are beginning to emerge, showing good oncological control, however, tumors with a central and endophytic location seem to possess an increased risk of treatment failure. Such tumors are likely to be subjected to a high volume of blood giving thermal protection to the cancerous cells. Arterial clamping during freezing might reduce this effect but at the same time subject the kidney to ischemia. The aim of this study was to evaluate the effect of renal artery clamping during cryoablation in a porcine survival model. METHODS: Ten Danish Landrace pigs (approximately 40 kg) underwent bilateral laparoscopic cryoablation with clamping of the right renal artery during freezing. The cryoablation consisted of a standard double-freeze cycle of 10-minute freeze followed by 8 minutes of thaw. Arterial clamping subjected the right kidney to 2 cycles of ischemia (10 minutes) with perfusion in between. After surgery, the animals were housed for 14 days prior to computed tomography perfusions scans, radioisotope renography, and bilateral nephrectomy. RESULTS: No perioperative or postoperative complications were experienced. Mean differential renal function was 44% (95% confidence interval: 42-46) in the clamped right kidney group and 56% (95% confidence interval: 54-58) in the nonclamped left kidney group, P < .05. The ±5% technical inaccuracy is not accounted for in the results. Mean maximum temperature between freeze cycles was 5.13°C (95% confidence interval: -0.1 to 10.3) in the clamped right kidney group and 22.7°C (95% confidence interval: -16.6 to 28.8) in the nonclamped left kidney group, P < .05. Mean cryolesion volume, estimated on computed tomography perfusion, was 12.4 mL (95% confidence interval: 10.35-14.4) in the clamped right kidney group and 6.85 mL (95% confidence interval: 5.57-8.14) in the nonclamped left kidney group, P < .05. Pathological examination shows a higher degree of vital cells in the intermediate zone of the cryolesions in the nonclamped left kidneys when compared with the clamped right kidneys. CONCLUSION: Arterial clamping increases cryolesion size by approximately 80%, and pathologic examinations suggest a decreased risk of vital cells in the intermediate zone. The clamped kidneys showed no sign of injury from the limited ischemic insult. This study was limited by being a nontumor model.

Preoperative Aspects and Dimensions Used for Anatomical Score Predicts Treatment Failures in Laparoscopic Cryoablation of Small Renal Masses.

OBJECTIVES: To determine the potential of the preoperative aspects and dimensions used for anatomical (PADUA) classification score as a predictive tool in relation to residual unablated tumor and disease-free survival (DFS) following laparoscopy-assisted cryoablation (LCA) of small renal masses. PATIENTS AND METHODS: A multi-institutional cohort of 212 patients with biopsy-verified T1N0M0 renal malignancies treated with LCA between August 2005 and September 2014 were retrospectively investigated with respect to oncologic outcomes. RESULTS: The preoperative PADUA score was found to be low (6-7 points) in 70 patients (33%), moderate (8-9 points) in 86 patients (40.6%), and high (10-14 points) in 56 patients (26.4%). The mean PADUA score was significantly higher in cases (n = 11) with residual unablated tumor (10.4 vs 8.1, p < 0.001) and in cases (n = 8) with local tumor recurrence (9.8 vs 8.1, p < 0.001) at a mean follow-up of 37 (95% confidence interval: 34-40) months. The estimated 2-, 3-, and 5-year DFS for patients with a moderate PADUA score was 96%, 94%, and 94% compared with 95%, 87%, and 81%, respectively, for patients with a high PADUA score (log-rank, p = 0.003). The PADUA score did not predict overall survival. CONCLUSION: The PADUA score significantly predicts residual unablated tumor and DFS following LCA. Further studies are needed to validate the efficacy of the PADUA score in relation to oncologic outcomes following ablative procedures.