Low clinical stage renal cell carcinoma: relevance of microvascular tumor invasion as a prognostic parameter

PURPOSE: Renal cell carcinoma is a tumor with unpredictable behavior and defining reliable prognostic factors would be extremely valuable in the clinical setting. Tumor stage, nuclear grade and tumor cell type are the main prognostic clinical parameters available. In this study we evaluated the role of microvascular involvement in the primary lesion for predicting tumor behavior in patients with low stage clinical disease. MATERIALS AND METHODS: A total of 95 patients with clinically localized renal cell carcinoma (stages T1-T2 Nx M0) underwent radical nephrectomy and/or nephron sparing surgery, and were followed for a median of 45 months. The impact of microvascular tumor invasion on disease progression and its correlation with known pathological outcomes (tumor size, nuclear grade and cell type) were studied. RESULTS: Microvascular tumor invasion was observed in 24 patients (25%), of whom 50% had disease recurrence. Of the 71 patients without microvascular invasion only 4 (6%) showed tumor recurrence. When microvascular invasion was correlated with other histological parameters, a significant statistical association was noted with tumor diameter, perirenal fat invasion, macroscopic extension to the renal vein, nuclear grade, lymph node metastasis and sarcomatous elements in the tumor. Multivariate analysis showed that microvascular invasion and the involvement of regional lymph nodes were independent predictors of disease recurrence. Concerning cancer specific survival, microvascular invasion and perirenal fat infiltration were the only factors related to death. CONCLUSIONS: Microvascular invasion is an independent and relevant clinical prognostic parameter for low clinical stage renal cell carcinoma.