Robot-assisted partial nephrectomy for totally endophytic renal tumors: Step by step standardized surgical technique and long-term outcomes with a median 59-month follow-up

Background: Treatment of totally endophytic renal tumors is a technically demanding surgery. While few studies show promising perioperative and short-term outcomes of robot-assisted partial nephrectomy (RAPN), its long-term outcomes remain undetermined. Materials and Methods: A retrospective analysis of 89 patients with totally endophytic renal tumors undergoing either RAPN (n = 52) or open partial nephrectomy (OPN; n = 37) in a tertiary-care institution between 2005 and 2015 was performed. Primary endpoint was to describe our transperitoneal RAPN surgical technique, while secondary endpoint was to compare the 5-year chronic kidney disease (CKD)-free survival, cancer-specific survival (CSS), and metastasis-free survival (MFS) rates between RAPN and OPN. Results: The median follow-up was 59 and 53 months for RAPN and OPN, respectively. Apart from increased prevalence of high complex tumors among RAPN cases (RAPN, 38.5% versus OPN, 16.2%; P = .037), and lower median eGFR (RAPN, 86 versus OPN 96 mL/minute/1.73 m ² ; P = .032), the remaining demographic characteristics were similar between the groups. At latest follow-up, the rates of local recurrence (P = .577), distant metastasis (P = .854), and cancer death (P = .187), and CKD upstaging ≥stage 3 (P = .728) did not differ between groups. The 5-year CKD upstaging-free survival was 96.2% versus 94.6% (log-rank, P = .746), MFS was 95.8% versus 97.1% (P = .876), and CSS was 100% versus 93.8% (log-rank, P = .102) when stratified by RAPN and OPN, respectively. Conclusion: RAPN is a safe and feasible option for treatment of totally endophytic renal tumors. Despite the increased prevalence of high tumor complexity and lower baseline renal function in the RAPN group, it achieved equivalent long-term oncologic control and functional outcome compared to OPN.