Functional Comparison of Renal Tumor Enucleation Versus Standard Partial Nephrectomy

Background: Tumor enucleation (TE) optimizes parenchymal preservation and could yield better function than standard partial nephrectomy (SPN), although data on this are conflicting. Objective: To compare functional outcomes for TE and SPN strategies. Design, setting, and participants: Patients managed with partial nephrectomy (PN) with necessary data for analysis of preservation of ipsilateral parenchymal mass (IPM) and global glomerular filtration rate (GFR) from two centers were included. All studies were required <2 mo before and 3–12 mo after surgery. Patients with a solitary kidney or multifocal tumors were excluded. Intervention: Partial nephrectomy. Outcome measurements and statistical analysis: Vascularized IPM was estimated from contrast-enhanced CT scans preoperatively and postoperatively. Serum creatinine-based estimates of global GFR were also obtained in the same timeframes. Univariable and multivariable linear regression evaluated factors associated with new-baseline global GFR. Results/limitations: Analysis included 71 TE and 373 SPN cases. The median preoperative global GFR was comparable for TE and SPN (75 vs 78 ml/min/1.73 m²; p = 0.6). The median tumor size was 3.0 cm for TE and 3.3 cm for SPN (p = 0.03). The median RENAL score was 7 in both cohorts. For TE, warm ischemia and zero ischemia were used in 51% and 49% of cases, respectively. For SPN, warm ischemia and cold ischemia were used in 72% and 28% of patients, respectively. Capsular closure was performed in 46% of TE and 100% of SPN cases (p < 0.001). Positive margins were found in 8.5% of TE and 4.8% of SPN patients (p = 0.2). The median vascularized IPM preserved was 95% (interquartile range [IQR] 91–100%) for TE and 84% (IQR 76–92%) for SPN (p < 0.001). The median global GFR preserved was 101%(IQR 93–111%) and 89% (IQR 81–96%) for TE and SPN, respectively (p < 0.001). On multivariable analysis, resection strategy, preoperative GFR, and vascularized IPM preserved were all significantly associated (p < 0.001) with new-baseline global GFR. Limitations include the retrospective design and the lack of resection outcome data. Conclusions: Our analysis suggests that TE has potential for maximum IPM preservation compared to SPN and may provide optimized functional recovery. Further investigation will be required to evaluate the clinical significance of these findings. Patient summary: Tumor enucleation for kidney cancer involves dissection along the tumor capsule and optimally preserves normal kidney tissue, which may lead to better functional recovery. The importance of this approach in various clinical settings will require further investigation. Renal tumor enucleation (TE) in renal cancer involves dissection along the pseudocapsule and may optimize preservation of parenchymal mass. The importance of this approach with respect to functional recovery after TE in various settings requires further investigation.