Multi-institutional analysis of robot-assisted partial nephrectomy for renal tumors >4 cm versus ≤4 cm in 445 consecutive patients

Background and Purpose: Robot-assisted partial nephrectomy (RPN) has emerged as a viable approach to minimally invasive surgery for small renal tumors. There are few reports of RPN for tumors >4 cm. Our objective was to evaluate outcomes of RPN for tumors >4 cm compared with RPN for tumors ≤4 cm in a large multi-institutional study. Patients and Methods: We reviewed data for 445 consecutive patients who underwent RPN by experienced surgeons at four academic institutions from 2006 to 2010. Patients were stratified into two groups according to radiographic tumor size. Patient demographics, perioperative outcomes, and oncologic outcomes were recorded. Results: A total of 83 of 445 (18.7%) patients had tumors >4 cm with a median radiographic tumor size of 5.0 cm (4.1-11 cm). Patients with tumors >4 cm had a higher proportion of hilar tumors (9.8% vs 4.7%, P<0.001), a higher mean R.E.N.A.L. nephrometry score (8.0 vs 6.3, P<0.01), longer warm ischemia time (WIT) (24 vs 17 min, P<0.001), and an increased rate of collecting system repair (72.2% vs 51.6%, P=0.006) compared with patients with tumors ≤4 cm. Functional outcomes and complications were similar between groups. There were no positive margins in patients with tumors >4 cm and only one recurrence. Conclusions: In the largest multi-institutional series of RPN for tumors >4 cm, we demonstrate safety, feasibility, and efficacy of RPN for tumors >4 cm. Patients with tumors >4 cm had a higher nephrometry score, longer WIT, and slightly higher estimated blood loss compared with patients who had tumors ≤4 cm, but there was no increased risk of adverse outcomes in the hands of experienced surgeons.