[750] Refining the Histologic Criteria of Perinephric and Renal Sinus Fat Invasion for Staging Clear Cell Renal Cell Carcinoma.

Hakan Aydin, Paul Elson, Brian Rini, Rick Baehner, Cristina Magi-galluzzi, Ming Zhou. Cleveland Clinic; Genomic Health, redwood

Background: Staging is critical for treatment and prognosis of clear cell renal cell carcinoma (CCRCC). Tumor invading into perinephric tissue/renal sinus fat is considered non-organ confined (pT3a). However, the histologic criteria of perinephric and renal sinus invasion are poorly defined. The purpose of this study is to determine the histologic criteria for invasion of perinephric tissue and renal sinus fat that correlate with clinical outcomes.
Design: 580 cases of clinically localized CCRCC were evaluated. The tumor perinephric tissue/renal sinus interface was classified according to the level of extension: tumor separate from perinephric/sinus tissue with a rim of renal parenchyma (level I) or fibrous capsule (level II); tumor penetrates into but not through a fibrous capsule (level III); or tumor extends into fat with smooth pushing border with a capsule (level IV) or without capsule (level V); or tumor extends into fat with desmoplastic response (level VI) or with infiltrative pattern (level VII); or tumor present in lymphovascular space in perinephric/sinus tissue (level VIII). The levels of tumor extension, tumor size and macroscopic vascular invasion were correlated to the 5-year recurrence-free survival using multivariable analysis and compared to historical staging and survival data.
Results: Case number and percentage for each level were as follows: I- 109 (19%), II-293 (51%), III-108 (19%), IV-35 (6%), V-10 (2%) and VI-VIII-25 (4%). The corresponding 5-year recurrence-free survival rates were: I- 96 ±2%, II-89 ±2%, III-77 ±4%, IV-57 ±9%, V-67 ±16%, and VI-VIII-25 ±9%. Multivariate analysis adjusted for tumor size and gross vascular invasion, showed that the level of extension was a significant independent prognostic variable (p<0.001). Estimated 5-year recurrence-free survival was 91+1% for patients with level I-II extension, 72%+4% for levels III-V, and 25+9% for levels VI-VIII. The 5-year survival rate for extension levels III-V is similar to the 5-year survival for AJCC stage II RCC (organ-confined disease, 73.7%), while that for levels VI-VIII is worse than AJCC stage III (non-organ confined disease, 53.3%).
Conclusions: Levels of perinephric/sinus tissue extension constitute a continuous risk factor for post-nephrectomy recurrence. Level III-V extension into perinephric/sinus tissue should be regarded as organ-confined while levels VI-VIII (tumor in fat with either desmoplasia, infiltrative pattern or lymphovascular space invasion) should be regarded as non-organ confined disease.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 11:15 AM

Platform Session: Section A, Monday Morning


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