Introduction

Robot-assisted partial nephrectomy (RAPN) has become a standard approach for small renal masses. Studies about RAPN are mostly retrospective and do not comprehensively capture factors and rates of scheduled RAPN that end with conversion to robotic radical nephrectomy (RRN). We describe the rate as well as patient and tumor characteristics for RAPN cases that convert to RRN using a multi-institutional prospective database.

Methods

We prospectively identified 430 patients who underwent attempted RAPN between 2014 and 2016 at multiple international centers as part of the Vattikuti Collaborative Quality Initiative (VCQI) database. These patients were permanently logged for RAPN prior to the date of surgery and remained in the prospective database regardless of whether intraoperative conversion to RRN was performed.

Results

5.3% (23 of 430 patients) of scheduled RAPN cases ended with RRN. Patients converted to RRN were older (mean age 64.3 vs. 59.1, p=0.01) with more comorbidities (mean Charlson age-adjusted comorbidity score 5.57 vs. 4.23, p=0.003) but had a similar pre-operative eGFR (70.7 to 79.2; p=0.09). Patients converted to RRN were more likely to have a tumor size >4cm (47.8% to 32.3%, p=0.05), an upper pole location (52.2% vs. 31.7%, p=0.04), a RENAL nephrometry score between 10-12 (30.4% vs. 11.5%, p=0.03), a higher mean RENAL nephrometry score (8.17 vs. 7.16, p=0.01), and intraoperative complications (30.4% vs. 3.9%, p=<0.0001). On pathological examination, patients converted to RRN were more likely to have invasion of perirenal fat (21.7% vs. 3.5%, p<0.0001), sinus fat (8.7% vs. 0.7%, p=0.0006), Gerota's fascia (4.8% vs. 0.5%, p=0.03), and involvement of segmental renal vein branches (14.3% vs. 0.5%, p<0.0001).

Conclusions

Prospective data collection of intended RAPN increases the detection of conversions to RRN. Our data suggests that difficult cases are initially attempted as RAPN, and the decision to perform RRN may be in part determined by tumor characteristics and patient comorbidities. Patients converted to RRN were more likely to have comorbidities, complex tumors, intraoperative complications, and poor pathologic features.

Funding

None