Functional Implications of Renal Tumor Enucleation Relative to Standard Partial Nephrectomy

To compare the surgical precision for optimizing nephron-mass preservation of tumor enucleation (TE) versus standard partial nephrectomy (SPN), with primary focus on functional outcomes. TE is presumed to optimize preservation of parenchymal mass/function but this has not yet been rigorously studied/quantified.

Robotic PN patients were included who had appropriate pre- and post-operative studies for analysis of parenchymal mass preservation specific to the operated kidney. CT or MR imaging and eGFR were required to be <2 months prior and 4-12 months after surgery. Parenchymal mass preservation and surgical precision were estimated for each technique, with precision defined as actual postoperative parenchymal volume/predicted postoperative parenchymal volume, presuming loss of a 5mm rim of parenchyma associated with tumor excision/reconstruction.

Analysis included 57 TE and 53 SPN. Median age, BMI, and tumor size were comparable. Percent parenchymal mass preserved in the operated kidney with TE was 96% (IQR=90-100%) versus 89% (IQR=83-96%) for SPN (p=0.003). Precision of excision/reconstruction was 101% (IQR=96-105%) for TE versus 94% (IQR=88-100) for SPN (p<0.001). On multivariable analysis, only TE correlated with improved surgical precision (coefficient=6.7, 95%CI=1.6-11.8, p=0.01). While preservation of global renal function also favored TE the differences were marginal (96% versus 93%), and statistical significance was not observed (p=0.2).

Our analysis, which specifically focuses on the functional implications of TE, demonstrates that TE maximally spares normal parenchyma compared to SPN. Thus far, functional differences remain marginal and not statistically significant. Clinical significance of these findings in various clinical settings will require further investigation.

Urology. 2016 Sep 07 [Epub ahead of print]

Robert H Blackwell, Belinda Li, Zachary Kozel, Zhiling Zhang, Juping Zhao, Wen Dong, Sarah E Capodice, Gregory Barton, Arpeet Shah, Jessica J Wetterlin, Marcus L Quek, Steven C Campbell, Gopal N Gupta

Department of Urology, Loyola University Medical Center, Maywood, IL., Stritch School of Medicine, Loyola University Medical Center, Maywood, IL., Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH., Department of Urology, Loyola University Medical Center, Maywood, IL. Electronic address: .