Introduction:

There is always the concern of aggressive pathology when patients are on active surveillance for small renal masses. Limited data exist on the characteristics of adverse pathologic features for small renal cell carcinomas (RCCs), especially at the national level.

Methods:

We identified patients with cT1aN0M0 RCCs (≤4cm) diagnosed between 2010 and 2016 who underwent partial or radical nephrectomy in the National Cancer Database. We developed an adverse pathologic score (APS) and each of the following pathologic features was assigned as one point: lymphovascular invasion, perinephric fat/renal sinus invasion, vein involvement, sarcomatoid features, tumor necrosis, and Fuhrman grade 3-4. Outcomes measurements included APS≥1 and overall survival (OS).

Results:

A total of 38,021 patients were included and 29.2% of them had APS≥1. The distribution of APS is shown in Figure(A). Specifically, ≤2cm, 2-3cm, and 3-4cm tumors had an estimated 21.1%, 29.7%, and 36.6% likelihood of having APS≥1, respectively. Distributions of APS by tumor size and sex are shown in Figure(B) and Figure(C). Multivariable logistic regression showed that compared with tumor size ≤2cm, 2-3cm (odds ratio [OR]=1.54) and 3-4cm (OR=2.04) tumors had a higher likelihood of having APS≥1. OS stratified by APS is shown in Figure(D) and Figure(E). Multivariable Cox regression showed that compared with APS=0, higher APS was associated with worse OS (hazard ratio [HR]=1.16, 1.46, and 2.22 for APS=1, APS=2, and APS≥3, respectively).

Conclusion:

For small RCCs, still a significant number of patients have adverse pathologic features. Aggressive pathologic features are associated with greater size. Decision making regarding active surveillance, renal mass biopsy, versus surgical intervention for small renal mass should take tumor size and APS into consideration.

Funding: N/A