Abstract: PD73-01
Sources of Funding: None

Introduction

Renal mass biopsy (RMB) provides important information about the aggressiveness of renal tumors and helps urologists in the treatment decision-making process. Although tumor tract seeding is exceedingly rare, we questioned whether tumor capsule violation from RMB is associated with increased risk of perinephric fat invasion. In this study, we evaluated the association between RMB and perinephric fat invasion in patients with localized RCC who underwent partial or radical nephrectomy.

Methods

We reviewed the National Cancer Database from 2004-2013 and identified patients who underwent partial nephrectomy (PN) or radical nephrectomy (RN) for clinical T1a, T1b, and T2a tumors. Patients were classified as upstaged if final pathology demonstrated perinephric invasion only. Patients who received neoadjuvant systemic treatment, those with clinically node positive disease, and tumors with renal sinus fat invasion were excluded. Logistic regression analysis was used to identify predictors of perinephric fat invasion. Descriptive statistics were then used to compare patient demographics and tumor characteristics between those with RMB and those without RMB.

Results

A total of 56,557 patients met our inclusion criteria. Pathologic upstaging to pT3a disease occurred in 3.7% of patients, of which 2.1% (1,191/56,557) had perinephric fat invasion only. RMB was performed in 3,740 (6.6%) patients. Age ≥70, Caucasian race, Charlson-Deyo score ≥2, and tumor size ≤4cm were associated with higher utilization of RMB. Perinephric fat invasion was identified in 2.0% of patients without RMB and in 2.9% of patients with RMB. Logistic regression demonstrated a significant association between RMB and perinephric fat invasion (OR 1.51, 95% CI 1.24 - 1.85) after controlling for confounders. As an additional control, RMB was not found to be associated with risk of upstaging to renal sinus fat invasion.

Conclusions

Perinephric fat invasion on final pathology is a rare finding in patients with clinically localized renal tumors. Although performed for relatively smaller tumors, RMB is associated with risk of upstaging to pT3a disease and this is limited to perinephric fat invasion. This finding may be secondary to pathologic artifact or confounding variables not accounted for in our multivariable model. Prospective studies to evaluate cancer specific outcomes, such as recurrence, are warranted to further investigate the clinical relevance of these findings.

Funding

None