675 Background: New baseline GFR is a major factor for cancer survivorship after renal cancer surgery. Parenchymal mass preservation is the predominant factor associated with functional outcomes after partial nephrectomy (PN). Contact surface area (CSA) between the tumor and parenchyma may impact parenchymal preservation and predict functional outcomes after PN. We evaluated CSA as a predictor of parenchymal mass and function preserved by PN. Methods: 419 patients managed with PN had necessary studies to evaluate preoperative and postoperative parenchymal mass and renal function within the operated kidney. Patients with multifocal renal masses were excluded. Parenchymal mass in the operated kidney and CSA were measured using contrast-enhanced CT < 2 months prior and 3-12 months after PN. CSA was calculated using mathematical formula: 2πrd, where r = radius and d = intraparenchymal depth of tumor. Pearson correlation evaluated relationships between CSA and parenchymal mass or GFR preservation. Multivariable linear regression assessed predictors for GFR preservation. Conceptually, the formula for CSA should function best for exophytic tumors, while predictive value for endophytic tumors may not be as strong. Results: Median tumor size and R.E.N.A.L. were 3.5 cm and 8, respectively. Median global/ipsilateral GFR preserved were 89%/79%, respectively. Median ipsilateral parenchymal mass preserved was 85% and significantly higher for exophytic masses (87% vs 83%, p = 0.001). Median CSA was 22.8cm2 and significantly less for exophytic masses (19.8cm2 vs 24.6cm2, p = 0.02). CSA associated modestly with both ipsilateral GFR and mass preserved ( r= 0.25 and 0.36, respectively, both p < 0.001). On multivariable analysis, CSA associated with ipsilateral GFR preserved for exophytic masses (p = 0.011), but not for endophytic ones (p = 0.27). Limitations include retrospective design. Conclusions: CSA associates with parenchymal mass and function saved after PN, although its utility appears to be greatest for exophytic rather than endophytic tumors. Further study will be required to validate the utility of CSA in different clinical settings.
PD07-11 TUMOR CONTACT SURFACE AREA AS A PREDICTOR OF FUNCTIONAL OUTCOMES AFTER PARTIAL NEPHRECTOMY
