Presentation Authors: Diego Aguilar Palacios*, Elvis R. Caraballo, Cleveland, OH, Hajime Tanakaa, Tokyo, Japan, Yanbo Wanga, Changchun, China, People's Republic of, Chalairat Suk-Ouichai, Bangkok, Thailand, Yunlin Ye, Guangzhou, China, People's Republic of, Lin Lin, Steven C. Campbell, Cleveland, OH
Introduction: Loss of renal function remains a major limitation of radical nephrectomy (RN) for renal cell carcinoma (RCC). RCC patients tend to be older and have significant comorbidities, including CKD, but the timeline of functional recovery and factors predictive of degree of renal compensation have not been well-defined.
Methods: A retrospective review was performed of all RN performed at our center from 2006-2016. 273 patients with available nuclear renal scan and imaging demonstrating non-metastatic RCC with preoperative GFR >15ml/min/1.73m2 were analyzed. GFR values were estimated by CKD-EPI preoperatively and up to 5 years after RN. Pre and postoperative volumes of the uninvolved kidney were measured by free-hand scripting from axial images at 3 mm intervals. Renal functional compensation was defined: percent change in GFR (postoperative GFR/preoperative GFR of preserved kidney). Renal parenchymal compensation was defined: percent change in parenchymal volume (postoperative volume/preoperative volume of preserved kidney). Multiple regression was used to identify predictive factors of renal compensation.
Results: Median age was 67 and 67% of patients were male. Comorbidities before RN included hypertension in 70%, 28% cardiovascular disease, 26% diabetes, 55% were active/former smokers, and 37% had CKD. Median BMI was 30. Locally advanced (â‰¥T3a) tumors were found in 53% and clear cell histology in 71% of cases. Renal functional compensation was observed at 2 weeks (median 110%) and increased during the first 3 months (median 126%) after RN. Functional stability was then observed to 5 years. The median percent increase in renal parenchymal volume at 3-12 months was 10%, but in addition, the functional efficiency per unit of parenchymal volume also increased 10% (GFR units/cm3 of parenchyma was 0.21 preoperatively vs. 0.23 postoperatively, p=0.004). Age [-0.11, p < 0.001], global preoperative GFR [-0.73, p < 0.001] and GFR of removed kidney [0.56, p < 0.001] were independent predictors of percent functional compensation.
Conclusions: Our data suggest that percent compensation of renal function after RN is greater in younger patients, when the global preoperative GFR is lower, and when the removed kidney has more robust function. Compensatory changes appear to progress over the first few months after RN followed by functional stability. Functional compensation appears to be due to increase in parenchymal mass and increased filtration efficiency of the remaining parenchymal mass, with both contributing in a substantial manner.