Can RENAL and PADUA Nephrometry Indices Predict Complications of Laparoscopic Cryoablation for Clinical Stage T1 Renal Tumors?

Abstract

Assessment of anatomical complexity with the RENAL (radius; exophytic/endophytic; nearness; anterior/posterior; location) and preoperative aspects and dimensions used for anatomical classification (PADUA) nephrometry indices is used to predict complications related to surgical extirpation treatment for patients with clinical T1a/b renal mass. This single center study aims to investigate the value of these indices to predict complications in a cohort of patients treated with laparoscopic cryoablation (LCA) for cT1 renal mass. Single institution data from consecutive LCA procedures were prospectively collected from December 2006 to April 2013. Renal mass anatomical complexity was categorized according to RENAL and PADUA indices. Comorbidity was assessed by the Charlson-index. Intraoperative complications (IOCs) were reviewed and categorized: blood loss >100 mL, conversion, tumor fracture, and incomplete ablation. Postoperative complications (POCs) were graded using the modified Clavien-index. Univariate and multivariate logistic regression models addressed the risk for complications. Ninety-nine LCA procedures were included. The median RENAL-score was 7.0 (standard deviation [SD] 1.7), and the median PADUA-score was 8.0 (SD 1.6). IOC occurred in 19 procedures (19%). The risk for IOC was significantly correlated (p<0.05) with tumor diameter (mm), surface, volume, the RENAL domains "R-size," "N-nearness to collecting system," "RENAL score," and the PADUA domain "diameter." In multivariate analysis with surgical complication as the independent variable, tumor diameter, surface, and volume were determining factors. A threshold was set for 35 mm tumor diameter, it being predictive for an increased risk for IOC performing LCA. Twenty-three POC occurred in 20 patients. On univariate analysis, the RENAL domain "nearness to collecting system," and no PADUA domains, had a significant association with POC. The RENAL score, and not the PADUA score, is associated with a higher risk for IOC. A noncategorized method of scoring tumor diameter showed a more significant correlation with the risk for IOC than the categorized method of the nephrometry indices. As a result a threshold diameter of 35 mm was established.