A Multi-Institutional Matched-Pair Analysis of Robotic Partial Nephrectomy for Single vs Multiple Ipsilateral Renal Masses.

Introduction: Nephron-sparing surgery is important in patients with multiple renal tumors, especially if associated with a solitary kidney or hereditary syndrome. Prior studies have shown partial nephrectomy (PN) of multiple ipsilateral renal masses to have good oncologic and renal function outcomes. We aim to compare renal function changes, complications, and warm ischemia time (WIT) of partial nephrectomy of a single renal mass (sPN) vs those of partial nephrectomy of multiple ipsilateral renal masses (mPN). Materials and Methods: We retrospectively reviewed our multi-institutional PN database. We matched robotic sPN and mPN patients ∼3:1 using "nearest neighbor" propensity score matching based on age, Charlson comorbidity index (CCI), total tumor size, and nephrometry score. Univariate analysis was performed, and multivariable models were fit controlling for age, gender, CCI, and tumor size. Results: Fifty mPN and 146 sPN patients were matched. The mean total tumor size was 3.3 and 3.2 cm, respectively (p = 0.363). The mean nephrometry score in both groups was 7.3 and 7.2, respectively (p = 0.772). Estimated blood loss (EBL) was 137.6 and 117.8 mL, respectively (p = 0.184). The mPN group had higher operative time (174.6 vs 156.4 minutes, p = 0.008) and WIT (17.0 vs 15.3 minutes, p = 0.032). There was no significant difference in the change in glomerular filtration rate (mPN -6.4% vs sPN -8.7%, p = 0.712). Complications (Clavien 2+) occurred in 10.2% of mPN and 11.3% of sPN patients (p = 0.837). A multivariable linear model predicts a nonstatistically significant difference of 1.4 minutes of additional WIT in the mPN group (p = 0.242). There was no statistical difference in complication rates between groups in a multivariable model (odds ratio 1.00, p = 0.991). Conclusions: Robotic PN in our multi-institutional matched comparison of mPN and sPN showed no difference in complications, renal functional outcomes, or EBL. mPN was associated with increased operative time and WIT, though the WIT difference was not significant on multivariable analysis.