1680 PREVALENCE AND RISK FACTORS FOR DEVELOPMENT OF METABOLIC SYNDROME AFTER RADICAL OR PARTIAL NEPHRECTOMY

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untreated localized RCC has not been well documented. This would provide a new baseline for measuring the impact of kidney cancer therapy on renal function. Our objective is to establish the natural history of renal function in patients who are managed by active surveillance (AS) for T1a RCC. METHODS: 45 patients with localized sporadic biopsy-proven RCC ⬍ 4 cm managed by AS were retrospectively identified from May 2003 to September 2010. Patients all had baseline estimated glomerular filtration rate (eGFR)⬎ 60 ml/min/1.73 m2 and normal contralateral kidney function. eGFR was calculated using the Modification of Diet in Renal Disease (MDRD) equation. The rate of developing eGFR ⬍60 ml/min/ 1.73 m2 was calculated. Kaplan-Meier analysis was used to estimate the percentage of freedom from CKD stage 3 at follow-up. RESULTS: Median follow up was 26(IQR12-43) months. Median age was 68(59-75) years. The median baseline eGFR was 81(7491) ml/min/1.73 m2. 12 (27%) patients had an eGFR ⬎ 90 (CKD stage 1) and 33 (73%) patients had an eGFR between 60 and 89 (CKD stage 2). 8 patients (17.8%) had eGFR ⬍60 (CKD stage 3) by the end of follow-up. The 3 year freedom from eGFR ⬍ 60 ml/min/1.73m2 in this cohort of patients is 80%. In the group of patients ⬎ 65 years old (26 out of 45 or 58%), 5 out of 26 patients (19%) had CKD stage 3 at the end of follow-up with a 75% 3-year freedom from eGFR ⬍ 60 ml/min/ 1.73m2. CONCLUSIONS: This is the first study, to our knowledge, to report the natural history of renal function in a cohort of biopsy-proven RCC patients undergoing AS. RCC patients may be at a higher risk for the development of renal dysfunction. The rate established in this study can be used in the future to compare with the rate of eGFR decline in patients who have undergone surgical or ablative treatment for RCC, and to assess the actual impact of these treatments on renal function. Source of Funding: None

1678 PARTIAL NEPHRECTOMY IS NOT ASSOCIATED WITH AN OTHER-CAUSE MORTALITY BENEFIT IN PATIENTS AGED >75 YEARS AND/OR MULTIPLE COMORBIDITIES WITH SMALL RENAL MASSES. Maxine Sun*, Montreal, Canada; Marco Bianchi, Milan, Italy; Quoc-Dien Trinh, Detroit, MI; Jens Hansen, Hamburg, Germany; Nawar Hanna, Zhe Tian, Montreal, Canada; Shahrokh Shariat, New York, NY; Paul Perrotte, Pierre Karakiewicz, Montreal, Canada INTRODUCTION AND OBJECTIVES: Partial nephrectomy (PN) may protect against other-cause mortality (OCM) relative to radical nephrectomy (RN) in patients with localized renal cell carcinoma (RCC). However, this benefit may not be applicable to patients with advanced age and/or multiple baseline comorbidities. We sought to quantify the effect of treatment type on OCM amongst patients with these characteristics. METHODS: Using the Surveillance, Epidemiology, and End Results Medicare-linked database, respectively 8736 (88%) and 1249 (12%) RN and PN patients with T1 RCC were identified (1988 –2005). To adjust for inherent differences between treatment types, propensitybased matched analyses was performed. Univariable and multivariable competing-risks regression analyses for prediction of OCM were performed according to treatment type. Sub-analyses were conducted in patients aged ⬎75 years and with ⬎2 comorbidities. RESULTS: Following propensity-based matched analyses, the 2- and 5-year OCM rates were 6.2 and 18.8% for RN vs. 6.1 and 17.3% for PN, respectively (P⫽0.28). Amongst patients aged ⬎75 years, the 2- and 5-year OCM rates were 9.0 and 26.0% for RN vs. 9.7 vs. 27.7% for PN, respectively (P⫽0.42). For the same time points, in patients with ⬎2 baseline comorbidities, the rates were 8.0 and 23.5% for RN vs. 7.5 and 20.2% for PN, respectively (P⫽0.19). Following adjustment for all covariates, no difference was recorded between PN and RN in the risk of OCM in the matched population (hazard ratio [HR]: 0.92, 95% confidence interval [CI]: 0.79 –1.06, P⫽0.25). Amongst patients

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aged ⬎75 years (HR: 1.17, 95% CI: 0.94 –1.48, P⫽0.16) and ⬎2 baseline comorbidities (HR: 0.89, 95% CI: 0.75–1.05, P⫽0.17), no difference was recorded for treatment type. CONCLUSIONS: While nephron-sparing has been associated with a protective effect on OCM, some elderly patients and/or those with multiple comorbidities at baseline may not benefit from PN. Amongst these patients, alternative treatment options may be recommended. Source of Funding: None

1679 PARTIAL NEPHRECTOMY VS. NON-SURGICAL MANAGEMENT FOR SMALL RENAL MASSES: A POPULATION-BASED COMPARISON OF DISEASE-SPECIFIC AND OVERALL SURVIVAL Elias S. Hyams*, Phillip M. Pierorazio, Jeffrey K. Mullins, Gwendolyn Clemens, Carol B. Thompson, Mohamad E. Allaf, Baltimore, MD INTRODUCTION AND OBJECTIVES: While partial nephrectomy (PN) is the standard of care for treatment of small renal masses (SRM), non-surgical management (NSM) has been an emerging strategy for older patients based on the frequently indolent behavior of these masses and competing risks of mortality. However, there has been a paucity of literature regarding the comparative outcomes of these treatment strategies. In this study, we performed a populationbased comparison of survival following PN vs. NSM. METHODS: Using the Surveillance, Epidemiology and End Results (SEER) cancer registry linked with Medicare claims (19882007), we identified patients ⬎65 years old with localized SRM (⬍⫽4cm). We identified subsets of patients undergoing PN or NSM, defined as no intervention within 6 months of diagnosis. The primary endpoints were disease-specific (DSS) and overall survival (OS), assessed using Kaplan-Meier survival estimation and Cox proportional hazards regression. RESULTS: 2,019 patients underwent PN and 4,054 patients underwent NSM during the study period. For PN patients, DSS and OS were 1965 (97%) and 1736 (86%), respectively, through a median follow-up of 5 years. For NSM patients, DSS and OS were 3747 (92%) and 2650 (65%), respectively, through a median follow-up of 4 years. When adjusting for demographic and comorbid variables, NSM was associated with an increased risk of overall mortality (HR⫽2.98, p⬍ 0.001). NSM was associated with an increased disease-specific mortality as well (HR⫽ 4.63, p⫽0.012), however the absolute difference compared with PN was low. For patients ⬎75 years old, there was no significant difference in disease-specific mortality between NSM and PN (HR 5.2, p⫽0.089). CONCLUSIONS: NSM is a safe approach for management of SRM in selected older patients. DSS is equivalent between NSM and PN for patients ⬎75 years old. While criteria for NSM require further elaboration, this approach should be carefully considered in the treatment algorithm for older patients. Source of Funding: None

1680 PREVALENCE AND RISK FACTORS FOR DEVELOPMENT OF METABOLIC SYNDROME AFTER RADICAL OR PARTIAL NEPHRECTOMY Ryan P. Kopp*, San Diego, CA; Reza Mehrazin, Memphis, TN; Wassim M. Bazzi, San Diego, CA; Jim Y. Wan, Robert W. Wake, Anthony L. Patterson, Memphis, TN; Christopher J. Kane, Ithaar H. Derweesh, San Diego, CA INTRODUCTION AND OBJECTIVES: Nephron Sparing Surgery (NSS) is a preferred option for the management of small renal masses, comparing favorably with radical nephrectomy (RN) for long⫺term oncologic efficacy and conferring superior renal functional

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preservation. Resultant renal endocrine dysfunction may impact systemic metabolism. We examined the prevalence and risk factors for development of metabolic syndrome (MSx) in patients who underwent RN and NSS. METHODS: Cohort analysis of 905 patients (610 RN/295 NSS, mean age 57.5 years, mean follow⫺up 5.8 years) who underwent RN or NSS for renal tumors at two institutions from 7/1987 to 6/2007. Patient and tumor characteristics, estimated Glomerular Filtration Rate (mL/min/1.73m2, eGFR), and metabolic parameters [Body mass index (BMI, kg/m2), dyslipidemia (DL), hypertension (HTN), and diabetes mellitus (DM)] were recorded. Primary outcome was MSx, defined by modified International Diabetes Federation Criteria including BMI⬎30 and any two of the following: DL, HTN, and DM—with de novo MSx occurring ⬎ 6 months after sugery. We analyzed data between RN and NSS groups. We utilized multivariate analysis (MVA) to elucidate risk factors for de novo MSx. RESULTS: No significant differences existed in mean follow⫺up, age, race, sex, and preoperative eGFR, BMI, HTN, DL, and MSx (RN 16.4% vs. NSS 19.0%). Preoperative DM was RN 20.8% vs. NSS 27.1%, p⫽0.034. Tumor size (cm) was significantly larger for RN (RN 7.0 vs. NSS 3.7, p⬍0.001). Postoperatively, significantly more de novo MSx existed in RN 13.9% vs. NSS 2.7%, p⬍0.001. Significantly greater postoperative eGFR⬍60 was noted for RN 45.7% vs. NSS 18%, p⬍0.001. MVA demonstrated RN (OR 4.03, p⫽0.001), postoperative eGFR ⬍60 (OR 2.79, p⬍0.001), preoperative BMI ⬎30 (OR 9.75, p⬍0.001), and preoperative DM (OR 4.20, P⬍0.001) as significantly associated development of MSx after surgery. CONCLUSIONS: Patients who underwent RN had significantly higher prevalence of de novo MSx compared to a similar cohort that underwent NSS. In addition to RN, preoperative BMI ⬎30, DM, and postoperative eGFR ⬍60 were significantly associated with development of MSx. Further investigation on impact of nephron loss on systemic metabolism is requisite. Source of Funding: None

1681 A NON-CANCER RELATED SURVIVAL BENEFIT IS ASSOCIATED WITH PARTIAL NEPHRECTOMY. Maxine Sun*, Montreal, Canada; Quoc-Dien Trinh, Detroit, MI; Marco Bianchi, Milan, Italy; Jens Hansen, Hamburg, Germany; Nawar Hanna, Montreal, Canada; Shahrokh Shariat, New York, NY; Paul Perrotte, Pierre Karakiewicz, Montreal, Canada INTRODUCTION AND OBJECTIVES: Partial nephrectomy (PN) may protect against other-cause mortality (OCM) relative to radical nephrectomy (RN) in patients with localized renal cell carcinoma (RCC). We sought to test this hypothesis in a national cohort of patients from the United States. METHODS: Using the Surveillance, Epidemiology, and End Results Medicare-linked database, respectively 4956 (82%) and 1068 (18%) RN and PN patients with T1a RCC were identified (1988 –2005). To adjust for inherent differences between treatment types, we relied on propensity-matched analyses. One-to-one matching was performed according to age, sex, race, baseline Charlson comorbidity index (CCI), baseline diagnosis of hypercalcemia and hyperlipidemia, socioeconomic status, population density, tumor size, and year of surgery. The 2- and 5-year OCM rates were computed using cumulative incidence. Univariable and multivariable competing-risks regression analyses for prediction of OCM were performed according to treatment type. Adjustment was made for cancer-specific mortality, patient age, CCI, sex, race, socioeconomic status, tumor grade, and year of surgery. RESULTS: Following propensity-based matching, baseline differences between RN and PN patients were similar (all standardized mean differences ⬍10%). The 2- and 5-year OCM rates after nephrectomy were 5.0 and 16.0% for PN vs. 6.9 and 18.1% for RN, respectively (hazard ratio [HR]: 0.85, 95% confidence interval [CI]: 0.71–1.03, P⫽0.096). In multivariable analyses, patients who underwent PN were significantly less likely to die of OCM relative to their PN-treated

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counterparts (HR: 0.82, 95% CI: 0.68 – 0.98, P⫽0.04). Increasing age (HR: 1.09, P⬍0.001), higher CCI (HR: 1.13, P⫽0.004), patients residing in rural areas (HR: 2.1, P⫽0.02), and tumor grade IV (HR: 4.2, P⫽0.007) were associated with a higher risk of OCM. CONCLUSIONS: With respect to PN, RN-treated patients are more likely to die of OCM after surgery, even after adjusting for cancer-specific mortality, as well as baseline CCI. In consequence, PN should be offered whenever technically feasible. Source of Funding: None

1682 COMPARATIVE EFFECTIVENESS OF PARTIAL AND RADICAL NEPHRECTOMY FOR LOCALIZED RENAL TUMORS ON SURVIVAL AND RENAL FUNCTION: A SYSTEMATIC REVIEW AND META-ANALYSIS Simon Kim*, R. Houston Thompson, Stephen Boorjian, Christopher Weight, Nathan Shippee, George Chow, Bradley Leibovich, Rochester, MN INTRODUCTION AND OBJECTIVES: The relative effectiveness of partial nephrectomy (PN) in comparison to radical nephrectomy (RN) for small renal masses (SRM) on survival and renal function remains unclear in light of the recent phase-3 clinical trial. We sought to perform a systematic review and meta-analysis of PN versus RN for localized renal tumors on all-cause mortality (ACM), cancer-specific mortality (CSM), and severe chronic kidney disease (CKD). METHODS: Cochrane Central Register of Controlled trials, MEDLINE, EMBASE, SCOPUS and Web of Science were searched from inception through 2011 for sporadic SRM that were surgically treated with PN or RN. Studies were eligible for inclusion if both treatment groups were included and the outcomes of ACM, CSM, and CKD were reported. We excluded studies that did not provide any comparative outcomes, or included hereditary kidney cancer. Generic inverse-variance with fixed-effects models were used to determine pooled hazard ratios for each outcome. The I® statistics was used to quantify the proportion of heterogeneity across studies that is due to real differences in clinical or methodological characteristics rather than chance alone. RESULTS: Overall, we identified 38 studies that were eligible for inclusion, of which only one study provided level-1 evidence from a randomized clinical trial. Data from 21, 23, and 9 studies were pooled for ACM, CSM, and severe CKD, respectively. Overall, 31,822 (76%) and 9,804 (24%) patients underwent RN or PN, respectively. From the pooled estimates of each outcome, PN correlated with an 11% risk reduction in ACM (HR: 0.89; p⫽0.001), a 26% risk reduction in CSM (HR: 0.74; p⫽0.006), and a 56% risk reduction in severe CKD (HR: 0.44; p⬍0.001). In each meta-analysis, there was moderate to high heterogeneity across studies with an I® statistic ranging from 59% to 88%. CONCLUSIONS: Our findings suggest that PN confers a survival advantage and lower risk of developing severe CKD following surgery for localized renal tumors. Our findings should be evaluated in the context of the low quality in the existing evidence and significant heterogeneity across studies. Future research should aim in obtaining high-level evidence to clearly demonstrate that PN confers superior survival and renal function to better inform patients, urologists, and clinical guidelines. Source of Funding: None