Single-Institution Experience with Robotic Partial Nephrectomy for Renal Masses Greater Than 4cm

Purpose: To review our institution's experience with robotic partial nephrectomy (RPN) for T1b and greater renal masses (>4cm [T1b+]) in terms of perioperative and oncologic outcomes relative to a contemporary cohort of patients with T1a renal masses (<4cm). Patients and Methods: 232 patients underwent RPN at our institution between 2008 and 2014. Demographics, R.E.N.A.L. nephrometry score, and operative, pathologic, and renal function outcomes, as well as complications, were compared between the two groups (T1a vs T1b+). Results: A total of 168 and 64 patients underwent RPN for T1a and T1b+ renal masses, respectively. T1b+ patients had a higher mean nephrometry score (8.2 vs 6.9), median pathologic tumor size (4.8 vs 2.6cm), median blood loss (200 vs 100mL), median warm ischemia time (23 vs 21 minutes), rate of conversion to radical nephrectomy (7.8% vs 1.2%), and rate of Clavien grade III or higher complications (14% vs 4.2%) compared with T1a patients. One patient was found to have disease recurrence in the T1a group, and no patients experienced recurrence in the T1b+ group. No patient died from the disease. Conclusions: The current series represents the largest single-institutional report of RPN for tumors >4cm. The higher complexity of tumors resected in this series did not preclude a safe and oncologically efficacious operation; however, Clavien grade III complications were more common in patients with tumors >4cm, likely from a higher rate of pseudoaneurysm. These data should be considered in preoperative counseling with patients before RPN for tumors >4cm.