Introduction

Nearly half of all patients undergoing partial nephrectomy (PNx) for cT1 tumors will have adverse final pathologic features such as high Fuhrman grade or pT3a disease. While renal mass biopsy can aid in the identification of high grade disease, tools to predict tumor upstaging are limited. Given that preoperative risk factors associated with pT3a upstaging are not well defined we sought to identify predictors of pT3a disease in patients undergoing PNx for cT1 disease.

Methods

A retrospective chart review was completed to identify patients with cT1 renal masses who underwent open or minimally-invasive PNx between 2000-2014. All patients with imaging sufficient for R.E.N.A.L Nephrometry scoring were included. The primary outcome was upstaging to pT3a disease at final pathology. All patients with benign final pathology were excluded. Univariate and multivariate logistic regression analyses were performed to identify characteristics independently associated with pT3a upstaging. All variables with a p-value of ≤ 0.1 on univariate analysis were included in the multivariate analysis.

Results

A total of 508 patients were identified, of which 449 (88%) had final pT1 and 59 (12%) had final pT3a disease. The etiology of pT3a upstaging was perinephric adipose extension in 69% (41/59), renal sinus fat invasion in 28% (14/59), and microscopic segmental or renal vein invasion in 7% (4/59). Patient age (p=0.012), ASA classification (p=0.005), preoperative radiologic tumor size (p=0.079), and high R.E.N.A.L Nephrometry Score complexity (p=0.017) were all associated with pT3a upstaging on univariate analysis. Multivariate analysis demonstrated a significant and independent association of patient age (p=0.025), preoperative radiologic tumor size (p=0.014), and high R.E.N.A.L Nephrometry Score complexity (p=0.019) with pT3a upstaging.

Conclusions

In patients who undergo PNx for cT1 disease, patient age, preoperative radiologic tumor size, and high R.E.N.A.L Nephrometry Score complexity represent readily measurable preoperative characteristics that are associated with increased risk of pT3a upstaging. The presence of these features may be utilized for operative planning to ensure adequate resection and negative margins in patients at increased risk for pathologic upstaging.

Funding

None