Prognostic evaluation of perinephric fat, renal sinus fat, and renal vein invasion for patients with pathological stage T3a clear‐cell renal cell carcinoma

Abstract

Objective To investigate the prognostic significance of various patterns of extrarenal extension that comprise pathologic stage T3a clear cell renal cell carcinoma among patients undergoing nephrectomy for non‐metastatic disease. Patients and Methods A retrospective review of 563 patients who underwent radical nephrectomy for pathologically‐confirmed T3aN0/NxM0 clear cell renal cell carcinoma between 1970 and 2011 was performed. All pathologic slides were re‐reviewed by one urologic pathologist. Associations of patterns of extrarenal extension (perinephric fat, renal sinus fat, and renal vein in isolation or in any combination) with disease progression, cancer‐specific mortality, and all‐cause mortality were evaluated on multivariable analyses. Results Overall, perinephric fat invasion, renal sinus fat invasion, and renal vein tumor thrombus were present in 144 (26%), 51 (9%), and 163 (29%) patients, respectively, with multiple patterns of extrarenal extension identified in 205 (36%) patients. No significant differences in survival outcomes were observed for isolated involvement of the perinephric fat invasion, renal sinus fat, or renal vein. However, patients with multiple patterns of extrarenal extension were at significantly increased risk of disease progression (HR 1.31, 95%CI=1.04‐1.65, P=0.020), cancer‐specific mortality (HR 1.64, 95%CI=1.27‐2.12, P<0.001), and all‐cause mortality (HR 1.32, 95%CI=1.08‐1.61, P=0.008). Conclusions Presence of multiple patterns of extrarenal extension is associated with higher risk for disease progression and cancer‐related death after radical nephrectomy compared to isolated involvement of the perinephric fat, renal sinus fat, or renal vein, which carry similar prognostic weight. If validated, these findings may help refine risk‐stratification of non‐metastatic T3a renal cell carcinoma by distinguishing patients with multiple versus one pattern of extrarenal extension.