Predictors of renal function in nephron sparing surgery for renal cell carcinoma in solitary kidneys

e16045 Background: Partial nephrectomy (PN) is an effective option for the treatment of renal cell carcinoma (RCC) in patients who need to preserve renal function. However, the oncologic safety and functional outcome after PN in solitary kidneys have not been fully examined. We assessed the outcomes after PN, and evaluated predictors of post-operative renal function. Methods: A retrospective analysis of the Columbia Urologic Oncology database found 1327 patients were treated for RCC from 1988 - 2008, of whom 38 consecutive patients underwent PN on a solitary kidney. Glomerular filtration rate (GFR) was estimated with the Modification of Diet in Renal Disease (MDRD) equation. Severe chronic kidney disease (CKD) and renal failure were defined as GFR of 15–30 cc/min/1.73m2 and GFR<15, respectively. Cox proportional hazards regression methods were used. Results: The study group included 30 men and 8 women with unilateral RCC. The mean age was 63.2 years (range 35–83). The mean estimated blood loss was 465cc, the mean tumor diameter was 3.9cm, and 6 (17%) of the patients had a positive surgical margin. 9 patients (30%) had recurrence of RCC at a mean of 23 months postoperatively. Recurrence occurred in the kidneys of 4 patients, lung in 3 patients, bone in 3 patients, and the ipsilateral adrenal gland in one patient. The mean preoperative GFR was 55.6, and the GFR decreased postoperatively by an average of 14.2%. No patients required postoperative hemodialysis. Preoperative GFR (HR=1.01, p<0.01) and the volume of kidney removed (HR=0.93, p=0.01) were associated with severe CKD and renal failure on a univariate Cox regression analysis, but were not independent predictors after adjusting for age, race, tumor stage and grade. Preoperative GFR, volume removed, age, tumor stage or grade were not independent predictors of RCC recurrence. Conclusions: PN in solitary kidneys pose difficult challenges for surgical and clinical management. Nephron sparing surgery for the treatment of RCC is feasible with acceptable morbidity and renal function outcome. The volume of renal parenchyma removed and the preoperative GFR are associated with renal function loss several months after surgery, and may be useful in predicting long-term renal function. No significant financial relationships to disclose.