626 PROGNOSTIC SIGNIFICANCE OF EXTENT OF RENAL VEIN INVOLVEMENT IN RENAL CELL CARCINOMA TREATED WITH RADICAL OR PARTIAL NEPHRECTOMY: EVIDENCE TO SUPPORT SUB-STRATIFICATION OF AMERICAN JOINT COMMITTEE ON CANCER T3A STAGE CLASSIFICATION

Abstract

INTRODUCTION AND OBJECTIVES: Patients with renal call carcinoma (RCC) tumor thrombus, have a broad range of survival, with a review reporting 5-year survival between 32% and 69% (Lawindy et al 2012). Controversy exists regarding which features are prognostic indicators in renal cell carcinoma. The American Joint Committee on Cancer (AJCC) and the Union International Centre le Cancer (UICC) modified the RCC staging system in 2010 (7th edition) to further differentiate renal vein involvement from inferior vena cava involvement. The current staging labels T3a as invasion into the renal vein or segmental (muscle containing) branches, T3b into the inferior vena cava below the diaphragm, and T3c into the vena cava above the diaphragm or into the wall of the vena cava. However, the staging does not differentiate between the extent of renal vein invasion. The objective of this study was to examine the prognostic significance of the degree of tumor thrombus invasion into branches of renal vein versus main renal vein. METHODS: We performed a retrospective review of our comprehensive cancer centerAEs database, identifying 129 patients with renal cell carcinoma with tumor thrombus extension into the renal vein that underwent radical or partial nephrectomy between 1990 and 2012. The patients were classified as having tumor extension into the main renal vein or segmental muscle containing branches of the renal vein. RESULTS: Ninety-two patients were classified as main renal vein and 37 were classified as segmental. On cox regression analysis segmental versus main renal vein was compared for disease specific and overall survival. Disease specific survival was significantly worse for main renal vein than segmental with a p value of 0.0351. Overall survival was not significant with a p value of 0.109. On multivariate analysis, controlling for pathology grade and tumor maximum diameter disease specific survival was still significantly worse for main renal vein than segmental with a p value of 0.043, and overall survival was again not statistically significant with a p value of 0.144. CONCLUSIONS: These findings suggest that the level of tumor thrombus within the renal vein has prognostic implications. This data supports the idea that the tumor staging guidelines should be further modified to take into account the degree of renal vein invasion.