Tumor complexity and the impact on MIC and trifecta in robot-assisted partial nephrectomy: a multi-center study of over 500 cases.

Purpose: To demonstrate the surgical feasibility of robot-assisted partial nephrectomy for complex renal masses with comparison of low/intermediate risk versus high-risk tumors according to the PADUA score.

Methods: Since 2008, 538 robot-assisted partial nephrectomies were performed at three German robotic centers. Both the MIC (margin, ischemia, complications) criteria and trifecta were applied.

Results: 60.1% of the tumors were of low and intermediate complexity (PADUA score 6-9, n = 326, group A), while 39.9% were highly complex (n = 212, score ≥ 10, B). Median clinical tumor size was 28 in A versus 37 mm in B (p < 0.001). There was no significant difference in terms of operative time (160 vs. 163 min, p = 0.20); ischemia time was slightly longer for B (11 vs. 12 min, p < 0.001). There were no significant differences for intra- (3.4%, A, vs. 6.6%, B, p = 0.10) or postoperative (21.5%, A, vs. 25.5%, B, p = 0.30) complication rates. There was a median eGFR decrease of - 9.4 (A) versus - 15.1 (B) ml/min (p < 0.001) on discharge. Histopathology revealed an R1 margin rate of 3.4% for the low/intermediate versus 6.1% for the high complexity group (p = 0.14). MIC criteria were fulfilled in 81.9% (A) versus 75.5% (B, p = 0.11) and trifecta criteria in 74.2% (A) versus 68.93% (B, p = 0.26).

Conclusions: Complication rates, histopathology results as well as quality criteria as indicated by MIC and trifecta were similar for high and low complexity groups. Therefore, robot-assisted partial nephrectomy is a safe and feasible option also in highly complex tumors.