Correlations of Tumor Size, RENAL, Centrality Index, Preoperative Aspects and Dimensions Used for Anatomical, and Diameter-axial–polar Scoring With Warm Ischemia Time in a Single Surgeon's Series of Robotic Partial Nephrectomy

ObjectiveTo evaluate the association of tumor size, renal nephrometry systems (RNSs), including RENAL, centrality index (C-index), preoperative aspects and dimensions used for anatomical, and diameter-axial-polar scoring, and individual categories of these RNSs with warm ischemia time (WIT).MethodsA single surgeon's series of robotic partial nephrectomy patients for whom RNS was available were identified from 2012 to 2013. Spearman's correlation was used to evaluate associations between the RNSs and individual categories and WIT.ResultsAnalysis was performed based on 69 patients with a median tumor size of 3.5 cm (interquartile range 2.6-4.2). Overall, each scoring system and tumor size were found to have a statistically significant association with the WIT, with the C-index system exhibiting the strongest correlation (coefficient: −0.609, P <.001), which was confirmed in the series beyond the surgeon's learning curve. In the subgroup of relatively small renal masses (<3 cm), there was a statistically significant association between the C-index, preoperative aspects and dimensions used for anatomical, and diameter-axial-polar systems with WIT. However, for tumors >3 cm, none of the RNSs was found to have a statistically significant correlation with WIT, except for the tumor size (coefficient: 0.354, P = .027). For subcategories, axial scoring was found to have a consistent statistically significant correlation with WIT.ConclusionOverall, each RNS and tumor size strongly correlated with WIT in patients undergoing robotic partial nephrectomy. However, the RNS outperformed tumor size in small (<3 cm) renal masses with an optimal discriminating power, whereas for relatively larger (>3 cm) tumors, WIT was significantly dependent on tumor size, and every centimeter may count.