LAUSR

OBJECTIVE To identify preoperative factors that predict positive surgical margins in partial nephrectomy. MATERIAL AND METHODS Using our institutional partial nephrectomy database, we investigated the patients who underwent partial nephrectomy for malignant tumors between January 2011 and December 2015. Patient, tumor, surgeon characteristics were compared by surgical margin status. Multivariable logistic regression was used to identify independent predictors of positive surgical margins. RESULTS A total of 1025 cases were available for analysis, of which 65 and 960 had positive and negative surgical margins, respectively. On univariate analysis, positive margins were associated with older age (64.3 vs. 59.6, p<0.01), history of prior ipsilateral kidney surgery (13.8% vs. 5.6%, p<0.01), lower preoperative eGFR (74.7 mL/min/1.73 m2 vs. 81.2 mL/min/1.73 m2, p=0.01), high tumor complexity (31.8% vs. 19.0%, p=0.03), hilar tumor location (23.1% vs. 12.5%, p=0.01), and lower surgeon volume (p<0.01). Robotic versus open approach was not associated with the risk of positive margins (p=0.79). On multivariable analysis, lower preoperative eGFR, p=0.01), hilar tumor location (p=0.01), and lower surgeon volume (p<0.01) were found to be independent predictors of positive margins. CONCLUSION In our large institutional series of partial nephrectomy cases, patient, tumor, and surgeon factors influence the risk of positive margins. Of these, surgeon volume is the single most important predictor of surgical margin status, indicating that optimal oncological outcomes are best achieved by high-volume surgeons.