Thompson, R. H.

348 Background: While the initial natural history after surgical resection for localized renal cell carcinoma (RCC) has been well-characterized, recurrence patterns for patients who experience late recurrence of disease continue to be defined. Here, we evaluated the clinical characteristics and survival of patients who experienced disease recurrence > 5 years following nephrectomy. Methods: We identified 1,454 patients who were treated with radical nephrectomy (RN) or nephron-sparing surgery (NSS) for unilateral, sporadic pT1-4NxM0 RCC between 1970-2000 and who had remained free of disease for 5 years after surgery. Late (> 5 years) recurrence was then recorded and was classified as renal (ipsilateral/contralateral kidney) recurrence and distant (all other sites) recurrence. The incidence of late recurrence was estimated using the Kaplan Meier method, and clinicopathological variables subsequent disease relapse were analyzed using Cox proportional hazard regression models. Results: Median follow-up after nephrectomy in the cohort here was 13.9 years (range 5.1-38.9). In total, 63 patients experience a late recurrence in the ipsilateral/contralateral kidney, at a median of 9.3 years (range 5.1-25.3) after surgery. 172 (11.8%) patients developed late distant metastases, at a median of 9.6 years (range: 5.1-26.6). Estimated recurrence-free survival at 10 and 15 years following nephrectomy was 97.3% and 95.2% for renal recurrence and 93.1% and 85.9% for distant recurrence, respectively. Increased tumor size (HR 1.1; p<0.001) was associated with a higher rate of late renal recurrence, while increased tumor size (HR 1.1; p=0.018), clear cell or collecting duct histology (HR 3.7; p<0.001), and tumor stage pT1b (HR 2.8; p<0.001), pT2a (HR 4.5; p<0.001), pT2b (HR 3.4; p=0.007), and pT3/4 (HR 5.1; p<0.001) were predictive of the development of late distant metastasis. Conclusions: Patients undergoing surgery for localized RCC remain at life-long risk of disease recurrence. Approximately 5% experience renal recurrence and 15% demonstrate distant relapse, during the ensuing 10 years. Continued investigation to identify potential site-specific predictors of late recurrence is necessary to guide postoperative surveillance regimens. No significant financial relationships to disclose.

321 Background: Factors that determine renal function after partial nephrectomy (PN) are not well defined, including the impact of cold vs. warm ischemia and the relative importance of modifiable and non-modifiable factors. We studied these determinants in a large cohort of patients with a solitary functioning kidney undergoing PN. Methods: In 1980–2009, 660 PN were performed at 4 centers for tumor in a solitary-functioning kidney under cold (n=300) or warm (n=360) ischemia. Data were collected in IRB-approved registries; follow- up averaged 4.5 years. Pre- and postoperative glomerular filtration rates (GFR) were estimated via CKD-EPI equation. Results: At 3 months after PN, median GFR decreased by equivalent amounts with cold or warm ischemia (21% vs. 22%, respectively, p=0.7) although median cold ischemic times were much longer (45 vs. 22 min. respectively, p<0.001). In multivariable analyses, increasing age, larger tumor size, lower preoperative GFR, and longer ischemia time were associated with decreased postoperative GFR (p<0.05). When percentage of parenchyma spared was incorporated into the analysis, this factor and preoperative GFR proved to be the primary determinants of ultimate renal function, and duration of ischemia lost statistical significance. Conclusions: This non-randomized comparative study suggests that long-term renal function after PN is determined primarily by the quantity and quality of renal parenchyma that can be preserved. Within the relatively strict parameters of conventional practice, i.e. predominantly short ischemic intervals and liberal use of hypothermia, ischemia time was not an independent predictor of ultimate renal function after PN. Nevertheless, type and duration of ischemia remain the most important modifiable factors during PN, and mandate further study. [Table: see text]