Impacts of Complete Endophytic Renal Tumors on Surgical, Functional, and Oncological Outcomes of Robot-Assisted Partial Nephrectomy

Objective: Complete endophytic renal tumors (CERTs) are the most challenging for robot-assisted partial nephrectomy (RAPN). This study aimed to determine the impact of CERT on outcomes of RAPN. Methods: All RAPN cases for localized renal tumor undertaken at Yokohama City University Hospital between 2016 and 2023 were enrolled. Tumor characteristics and surgical, functional, and oncologic outcomes of RAPN were compared between CERT and non-CERT groups. Results: Consecutive 666 patients were enrolled, and 76 (11.4%) were identified as CERT (3 points of "E" score). CERT showed smaller tumor diameters (p < 0.001), more predominant hilar tumor (p = 0.029), higher "N" scores (p < 0.001) and "L" scores (p = 0.006) than non-CERT. The CERT group showed longer warm ischemia times (p < 0.001), more frequent positive surgical margins (p = 0.028), and relatively lower trifecta achievement rates (p = 0.101) than the non-CERT group. In multivariable analysis, the CERT was an independent predictor for trifecta achievement but not for pentafecta achievement. Conclusions: CERT was associated with longer warm ischemia time, positive surgical margin, and lower trifecta achievement, but not with surgical complication and pentafecta achievement in RAPN. This study suggested that CERT had limited influence on long-term renal functional preservation; however, it had strong impacts on short-term surgical outcome.