PARTIAL NEPHRECTOMY IN A COHORT OF “ENUCLEORESECTIVE” CENTERS: INSIGHTS FROM THE SURFACE-INTERMEDIATE-BASE (SIB) MARGIN SCORE INTERNATIONAL CONSORTIUM

INTRODUCTION AND OBJECTIVES: Detailed reporting of resection strategies (RS) and resection techniques (RT) for tumor excision during partial nephrectomy (PN) is lacking in the current literature. As such, we evaluated the relationship between patient/ tumor characteristic, RT, and outcomes at Centers from the Surface- Intermediate-Base (SIB) Margin Score International Consortium that pursue the “Enucleoresective” strategy during Partial Nephrectomy. METHODS: After institutional review board approval, data were prospectively collected from a cohort of patients undergoing NSS at 16 high-volume Centers across the U.S. and Europe over a 6 months enrollment period. RT was classified according to the SIB scoring system. RS was classified as “enucleative”, “enucleoresective” or “resective” according to the most prevalent RT performed in each centre’s cohort. Descriptive and comparative analyses were performed in the six enucleoresective RS centers (ERC). RESULTS: Overall, 507 patients were enrolled in the study. The RT was classified as pure or hybrid enucleation (E, SIB 0-2), pure or hybrid enucleoresection (ER, SIB 3-4), and resection (R, SIB 5) in 266 (52.5%), 150 (29.6%) and 91(17.9%) patients, respectively in the overall cohort, while in 53 (33.1%), 83 (51.9%) and 24 (15.0%) patients in the ERC. Demographic data, comorbidity scores, surgical indication and approach and PADUA score did not significantly differ between the E, ER and R groups in the ERC. Tumors >4.0 cm were 21 (40.4%), 41 (49.4%) and 4 (16.7%) in the E, ER and R groups (p¼0.02), respectively. A clampless strategy was used in 19.2%, 13.2% and 8.3% of patients (p>0.05). Median WIT was 19 (15-24), 17 (14-23) and 17 (15- 21) minutes in the E, ER and R groups (p>0.05). Surgical postoperative complications were recorded in 7.5%, 13.2% and 4.2% of patients (p¼0.05). Positive surgical margins rate was 7.0%, 13.4% and 0% of patients, respectively (p>0.05). Trifecta outcome was achieved in 67.2%, 71.6% and 73.7% of patients for the E, ER and R groups (p>0.05). CONCLUSIONS: Through objective quantification of RT using a novel standardized reporting instrument, we were able to compare PN outcomes in a prospective multi-institutional international cohort. Overall, at centers that pursue enucleoresective technique, pure/ hybrid enucleation is not uncommon (33.1%). ER and E are performed in a significantly higher proportion of tumors >4 cm compared to R. Although ER was associated with a higher rate of complications, Trifecta outcomes were comparable among resection techniques.