Introduction:

Partial nephrectomy (PN) is a standard of care for amenable localized renal masses. While oncologic outcomes are generally favorable, functional outcomes of standard margin PN (SPN) are inherently tied to preserved parenchymal mass where preservation is limited by the goal of avoiding sharp incision into the tumor. Tumor enucleation (TE) PN is an alternative approach using a natural plane of dissection around the tumor pseudocapsule to maximize parenchymal preservation. We aimed to evaluate perioperative, functional, and oncologic outcomes for TE compared to SPN.

Methods:

A total of 467 patients ≥18 years of age undergoing robotic-assisted TE (N=176) or SPN (n=291) were included (2008-2020). Baseline demographic and tumor characteristics were tabulated and found to be comparable between the two groups for age, sex, race, tumor size, cT stage, RENAL nephrometry, and final histology (all p>0.05). Comparative effectiveness of each approach on perioperative, renal functional, and oncologic outcomes was assessed. Multivariable linear and logistic regression models were constructed to compare outcomes while adjusting for other factors.

Results:

Among patients with hilar clamping (TE 62.4% vs. SPN 96.5%, p<0.001), warm ischemia time was lower for TE (median 15 vs. 23 minutes, p<0.001). TE patients had lower EBL (median 25 vs 150mL, p<0.001), operative time (median 151 vs. 212min, p<0.001), length of stay (median 1 vs. 2 days, p<0.001), and fewer major and minor complications (both p<0.002). Positive margin rates were higher for TE vs. SPN (8.5% vs. 3.4%, p=0.04) with similar rates of recurrence (2.3% vs. 3.4%) at median 4.1 years follow-up. While baseline renal function was comparable (median eGFR 75.8 vs. 77.6, p=0.56), renal function in the first year was better preserved with TE (median eGFR 74.4 vs. 67.8, p<0.001) with a mean +7.9 eGFR (p<0.001) maintained after adjustment for preoperative eGFR (+0.70 per point, p<0.001), cT stage, age (-0.21 per year, p=0.005), sex, race, body mass index, approach, and presence of cystic component (+6.3, p=0.04).

Conclusion:

TE enables improved perioperative outcomes and preserves greater renal function for patients compared to SPN. While positive margin rates are higher, longer-term recurrence rates are no different suggesting pseudocapsule disruption during TE may have limited impact on oncologic outcomes relative to sharp incision with SPN.

Funding: N/A