Prognostic Impact of Muscular Venous Branch Invasion in Localized Renal Cell Carcinoma Cases
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PURPOSE: Beginning with the 2002 American Joint Committee on Cancer staging system, renal sinus muscular venous branch invasion has prognostic equivalence with renal vein invasion in renal cell carcinoma cases. To validate this presumed equivalence we compared patients with isolated muscular venous branch invasion to those with renal vein invasion and those with no confirmed vascular invasion. MATERIALS AND METHODS: From routine cataloging at our institution we identified 500 patients who underwent partial or radical nephrectomy from 2003 to 2008. After excluding patients with metastasis or noncortical renal cell carcinoma pathology we identified 85 with positive muscular venous branch invasion (+). The 259 patients with pT1-2 muscular venous branch (-) invasion and the 71 with renal vein (+) invasion served as comparison groups. We used a multivariate Cox model to control for tumor characteristics using the Kattan renal cell carcinoma nomogram. RESULTS: On multivariate analysis the risk of recurrence in the pT1-2 muscular venous branch invasion (-) group was lower than in the muscular venous branch invasion (+) group (HR 0.06, 95% CI 0.02-0.18, p < 0.001). Patients with renal vein invasion (+) had a recurrence rate similar to that in those with muscular venous branch invasion (+) (HR 0.80, 95% CI 0.39-1.65, p = 0.6). The overall survival rate was higher in the muscular venous branch invasion (-) group than in the other groups. CONCLUSIONS: Patients with muscular venous branch invasion have an outcome inferior to that in patients with pT1-2 disease. This confirms the adverse prognosis of muscular venous branch invasion and supports pathological up-staging. The prognosis of muscular venous branch invasion is similar to that of renal vein invasion, although we cannot exclude the possibility of a difference. Our findings underscore the importance of close patient followup and careful pathological assessment of the nephrectomy specimen.
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