Abstract: PD66-07
Sources of Funding: none

Introduction

While a nephron-sparing approach for renal tumors is desired in order to maximize renal function, technical factors related to tumor complexity can make the decision challenging. We therefore created a preoperative prediction tool for renal function outcomes at various time points following partial nephrectomy (PN) and radical nephrectomy (RN) to help guide the choice of surgical approach.

Methods

The Mayo Clinic Nephrectomy Registry was queried for patients who underwent PN or RN for a renal tumor between 1997-2013. Exclusions were nodal or distant metastases, venous tumor thrombus on imaging, and preoperative estimated glomerular filtration rate (eGFR) <15 mL/min. Parsimonious linear regression models predicting eGFR were created for PN and RN using backward selection of candidate preoperative predictors, and eGFR predictions at 1 year are presented. Adjusted R², a value ranging from 0-1 that represents the proportion of total variation in eGFR explained by the model, was used to quantify predictive ability.

Results

The analytic cohort included 1525 and 935 patients undergoing PN and RN, respectively. Mean (SD) preoperative eGFR and tumor size were 72 (20) mL/min and 3.4 (1.9) cm, respectively, for patients undergoing PN, and were 65 (18) mL/min and 7.1 (3.8) cm, respectively, for patients undergoing RN. The model for PN included age, presence of a solitary kidney, smoking status, performance status, BMI, preoperative eGFR, tumor size, and open vs lap surgical approach (R²=0.78), while the model for RN included age, diabetes, BMI, preoperative eGFR, tumor size, and surgical approach (R²=0.68). Using the models, a 68 year-old, non-smoking, non-diabetic, ECOG 0, binephric patient with a BMI of 20kg/m², a preoperative eGFR of 100mL/min, and a 6.5cm renal mass will have a predicted eGFR of 85 mL/min following open PN and 63 mL/min following laparoscopic RN at 1 year. If the patient was instead 50 years old, diabetic, with a preoperative eGFR of 80mL/min and a 2.5cm mass, predicted eGFR would be 78 mL/min following laparoscopic PN and 56 following laparoscopic RN at 1 year.

Conclusions

We created a prediction tool for renal function following RN and PN. If validated, this tool may be useful during patient counseling by providing personalized predicted renal function outcomes.

Funding

none