Presentation Authors: Toshio Takagi*, Kazuhiko Yoshida, Tsunenori Kondo, Junpei Iizuka, Hirohito Kobayashi, Hideki Ishida, Masayoshi Okumi, Kazunari Tanabe, Tokyo, Japan
Introduction: The ideal enucleation in robot-assisted laparoscopic partial nephrectomy (RAPN) is complete preservation of the parenchyma. However, in reality, a certain amount of parenchyma is damaged during tumor resection or tumor bed reconstruction. The contact surface area (CSA) between the tumor and the parenchyma is a proposed predictor of postoperative renal function, and several studies have reported its validity. We presumed that the effect of the CSA on parenchymal preservation is greater in the enucleation technique than in the standard partial nephrectomy because in the enucleation technique, the effect of resection volume of the normal parenchyma remains minimal. The aim of this study was to evaluate the change in operated parenchymal volume during RAPN limited to the enucleation technique and analyze the predictors of the decrease in operated parenchymal volume, including the CSA.
Methods: The study subjects were 129 patients who underwent RAPN for T1 renal tumors using the enucleation technique. Measurements for parenchymal volume, tumor volume, and CSA were obtained in the venous phase on enhanced CT and calculated using Mimics 20.0 and 3-matic 12.0 (Materialise N.V.). All measurements, such as volumetric and renal function analysis, were performed at < 2 months before and 6 months after surgery.
Results: The mean age was 56 years, and the mean tumor size was 33mm. The mean tumor volume was 27 cc, and the mean CSA was 23 cm2. In the complete cohort, the mean preoperative and postoperative normal parenchymal volumes for the operated kidney were 158 cc and 142 cc, respectively. The mean change in parenchymal volume in the operated kidney was -10%. In contrast, the mean change in global estimated glomerular filtration was -4.5%. A univariate analysis revealed that RENAL score, CSA, tumor volume, and warm ischemia time were associated with the change in the operated kidney parenchymal volume. However, larger CSA was the only independent predictor of decreased operated parenchymal volume of < 10 cc in multivariate analysis.
Conclusions: The CSA was a strong predictor of the decrease in the parenchymal volume in the operated kidney during RAPN performed using the enucleation technique for T1 renal tumors.