PREDICTIVE FACTORS OF POSITIVE SURGICAL MARGIN IN NEPHRON_SPARING SURGERY.A PROSPECTIVE MULTICENTER ITALIN STUDY 8THE RECORD 1 PROJECT)

Introduction/Aim: Surgical margins represent an oncological short-term surrogate outcome of nephron-sparing surgery (NSS). The aim of this study was to analyze predictive factors of positive surgical margin in a multicenter prospective study of NSS in Italy (RECORd Project). Materials and Methods: 1,075 patients treated with NSS, between January 2009 and December 2012, were evaluated. A univariate and a multivariate logistic regression of perioperative variables for positive surgical margin (PSM) were performed. Results: PSM, compared to negative surgical margins (NSM), were associated with a higher mean age of patients (65.5 vs. 61.8, p=0.02), a relative and absolute indication rate (38.6% vs. 19.7%, p=0.002) and polar superior lesions’ rate (54.5% vs. 27.5%, p=0.01; Table I). Patients treated with mini-invasive (VLP and robot-assisted) approach present lower PSM rate, compared to NSM (13.2% vs. 43.7%, p=0.01). At histopathologic examination, extra capsular lesions were higher in PSM, compared to NSM (11.3% vs. 4.0%, p=0.02). At multivariate logistic regression, open approach (odds ratio (OR)=2.1, 95% confidence interval (CI)=1.04-4.27, p=0.04), polar superior lesion (OR=2.9, CI=1.56-5.35, p=0.01) and pathologic extra capsular lesion (OR=2.9, CI=1.05-7.90, p=0.04) were confirmed as significant predictive factors of positive surgical margins. Conclusion: Tumor renal site represents an important nephrometric pre-operative characteristic predictive of PSM. Extracapsular lesions are also correlated with a higher risk of PSM. Mini-invasive approach seems to present lower PSM rate for optical magnification; however, these data should be revised assessing similar pre-operative conditions in both approaches.