Outcomes of robot-assisted partial nephrectomy in patients with complex renal tumours and pre-existing chronic kidney disease in a multi-institutional, multinational database

INTRODUCTION & OBJECTIVES: Partial nephrectomy can help preserve renal function, but may be more challenging in patients with complex tumours. We compare outcomes of robot-assisted partial nephrectomy (RAPN) for complex tumours in patients with and without pre-existing chronic kidney disease (CKD). MATERIAL & METHODS: Using the Vattikuti Collective Quality Initiative (VCQI) database (representing patients and surgeons from 11 centers across 4 continents), we identified 250 patients undergoing RAPN for complex tumours (identified by RENAL or PADUA score of >10). Peri-operative (estimated blood loss [EBL], warm ischemia time [WIT], complications and surgical margins) and functional outcomes (eGFR at 12-month follow-up) were assessed and stratified by preoperative CKD (CKD stage 3 or greater; n=33, 13.2%) vs. no significant CKD (eGFR >60 ml/min/1.73 m2; n=217, 86.8%). RESULTS: Overall, patients had a median body mass index of 25.7 (23.3-28.9) kg/m2and pre-operative eGFR of 83 (70-98) ml/min/1.73 m2 respectively. 48.4% tumors were >4 cm radius and 29.6% entirely endophytic. 95 (38%) tumours were posterior, 118 (47.2%) mid-polar and 67.2% had renal sinus involvement on preoperative imaging. Patients with CKD were older (median age 62 vs. 54; p=0.001), had higher median age-adjusted Charlson comorbidity score (5.5 vs. 2; p<0.001) and significantly larger tumours (median 4.7 vs. 4 cm; p=0.036) than patients without CKD. There were no significant differences in other tumour characteristics. Perioperatively, there were no significant differences in median WIT (24.5 vs. 22.5 min; p=0.5), operative (OR) time (175 vs. 180 min; p=0.2) and EBL (200 vs. 200 ml; p=0.9) between patients with CKD vs. without. Overall, 22 patients (12.1% in CKD group vs. 8.8% in non-CKD group; p=0.6) required intraoperative blood transfusion. A total of 26 patients overall experienced postoperative complications, of which 9 (3 in CKD group and 6 in non-CKD; p=0.09) were Clavien Grade 3 or higher. Positive surgical margin rates were comparable in the two groups (9.1% and 6.0% in CKD and non-CKD group, respectively). Patients with preoperative CKD had a greater percent decrease in eGFR at median 12-month follow up (4.06% vs. 0.3%; p=0.05). CONCLUSIONS: Despite the surgical challenges, RAPN for patients with complex renal tumours is safe and feasible, even for patients with CKD. Perioperative and functional outcomes 1 year after surgery appear acceptable, despite heterogeneity in surgical techniques, experience and patient population across multiple centers.