RESECTION TECHNIQUES FOR NEPHRON SPARING SURGERY (NSS) VARY: INSIGHTS FROM A PROSPECTIVELY COLLECTED MULTI-INSTITUTIONAL COHORT HARNESSING THE SURFACE-INTERMEDIATE-BASE (S.I.B.) MARGIN SCORE (SIB INTERNATIONAL CONSORTIUM)

INTRODUCTION AND OBJECTIVES: Resection methodology is rarely reported in current nephron sparing surgery (NSS) literature. Yet, a relationship between resection technique (RT) and complication rates, preserved parenchymal volume, surgical margins and oncologic outcomes likely exists. Our aim was to evaluate the newly proposed Surface-Intermediate-Base (SIB) Margin score as a standardized reporting system of RT in a cohort of patients undergoing NSS at 16 high-volume Centers across the U.S. and Europe. METHODS: After institutional review board approval, data were prospectively collected over a 6 months enrollment period. RESULTS: 507 patients were enrolled in the study. The mean number of patients included per center was 32 (range 11-90). A mix of open (150, 29,4%), laparoscopic (67, 13,2%) and robotic (290, 57%) approaches were harnessed for NSS. Median (IQR) preoperative tumor size for the entire cohort was 3,10 cm (2,50 e 4,30). Based on nephrometric assessment, 195 (38,5%), 188 (37,1%) and 114 (22,5%) tumors were classified as low, moderate, and high anatomic complexity, respectively. At pathological analysis, 30 (5,9%) positive surgical margins were recorded. Overall, the Trifecta outcomes (defined as absence of perioperative complications, negative surgical margins and WIT< 25 min) were achieved in 370 (73%) of patients. Figure 1 summarizes clinicopathologic and RT data in the cohort. CONCLUSIONS: Standardized reporting of resection technique is lacking in the current NSS literature. We recently introduced a standardized scoring system, the SIB Margin score, which quantitates the salient aspects of resection approaches after PN through a visual analysis of the intrarenal portion of the specimen immediately after surgery. Harnessing this systematic characterization of renal mass RTs, we for the first time demonstrated in an international multi-institutional cohort that resection approaches vary and that renal tumor enucleation is employed quite frequently even at institutions that do not support its ubiquitous use. These data lay the groundwork for determining whether RT is a modifiable variable for functional and oncologic outcomes in patients who undergo NSS.