Login to Access Video or Poster Abstract: MP59-16
Sources of Funding: None

Introduction

Vascularized parenchymal mass preservation (VPMP) can be measured before and after partial nephrectomy (PN) and appears to be an important contributor to functional outcomes. In this study, we assess the functional impact of VPMP in a large cohort of patients and evaluate potential predictive factors.

Methods

A total of 401 patients managed with PN for a renal mass at our center with necessary studies to determine VPMP and function preserved within the operated kidney were analyzed. VPMP was measured from CT scans <2 months prior and 3-12 months after PN. Renal function was estimated by glomerular filtration rate (GFR), using the MDRD-2 formula. Patients with 2 kidneys were also required to have split renal function from nuclear renal scans within the same timeframes, and all analyses focused on the operated kidney. Recovery from ischemia was defined as percent GFR preserved in the operated kidney normalized by percent VPMP. Pearson correlation evaluated the relationship between renal function preservation and VPMP. Multivariable logistic regression assessed predictors for VPMP.

Results

Eighty-seven patients (22%) had a solitary kidney, while 314 patients (78%) had a contralateral kidney. Median tumor size was 3.5 cm and median R.E.N.A.L. score was 8. Cold and warm ischemia were utilized in 151/250 patients, and median ischemia times were 27/21 minutes, respectively. Median preoperative vascularized parenchymal mass in the operated kidney was 197 cm3 (IQR: 153-246) and median postoperative vascularized parenchymal mass was 157 cm3 (IQR: 122-202), resulting in median 84% VPMP. Pearson’s correlation analysis showed that GFR preservation correlated strongly with VPMP (r=0.63, p<0.001). Recovery from ischemia was suboptimal (<80%) in 61 patients (15%), while suboptimal VPMP (<80%) was a more common adverse event, occurring in 140 patients (35%)(p<0.05). Multivariable analysis demonstrated that increased tumor size and R.E.N.A.L. score correlated with reduced VPMP (p=0.043 and <0.001, respectively), and solitary kidney status correlated with increased VPMP (p=0.006). Increased ischemia time also correlated with reduced VPMP (p=0.027), reflecting the complexity of surgery.

Conclusions

Our data suggest that vascularized parenchymal mass preserved (VPMP) correlates strongly with functional outcomes after PN. Larger tumor size and increased tumor complexity correlate with reduced VPMP while VPMP tended to be greater for solitary kidneys.

Funding

None