Introduction

Loss of nephron mass is the predominant factor associated with functional outcomes after partial nephrectomy (PN), and can be due to excised parenchymal mass (EPM) and/or devascularized parenchymal mass (DPM). In this study, we are going to evaluate the importance of EPM and DPM relative to functional recovery after PN.

Methods

A total of 168 patients managed with PN had necessary studies to determine EPM and DPM and evaluate parenchymal mass changes and functional loss within the operated kidney. Parenchymal mass loss in the ipsilateral kidney was measured from CT scans <2 months prior and 3-12 months after PN. EPM was estimated from pathologic specimen by subtracting tumor volume from specimen volume. Tumor volume was measured from preoperative CT, and specimen volume estimated from defatted specimen weight after adjusting for tissue density and proportionate changes related to lack of blood flow ex vivo. DPM was defined as total parenchymal mass loss minus EPM. Patients with a contralateral kidney were required to have nuclear renal scans within the same timeframes. Pearson correlation evaluated the relationship between GFR preservation and parenchymal mass loss, and multivariable analysis assessed predictors for DPM.

Results

Median tumor size was 3.4 cm, median R.E.N.A.L score was 7, and 32 patients (19%) had a solitary kidney. Warm/cold ischemia were utilized in 100/68 patients, respectively. Median EPM and DPM were 9cm3 and 16cm3, respectively. Median GFR preserved was 89% globally and it was 79% in the operated kidney. While total parenchymal mass loss and DPM correlated strongly with GFR preservation in the operated kidney (both p<0.001), EPM failed to correlate with functional outcomes (r<0.2). Preoperative GFR and endophytic status associated with DPM on multivariable analysis.

Conclusions

Devascularization during reconstruction associates strongly with functional outcomes after PN, which has important implications regarding surgical technique. Prospective study will be required to further evaluate the relative values of EPM and DPM.

Funding

none