Impact of Microscopic Wall Invasion of the Renal Vein or Inferior Vena Cava on Cancer-specific Survival in Patients with Renal Cell Carcinoma and Tumor Thrombus: A Multi-institutional Analysis from the International Renal Cell Carcinoma-Venous Thrombus Consortium

Background: Microscopic vein invasion (MVI), with local destruction and invasion of the endothelium by tumor, is of controversial predictive value in renal cell carcinoma (RCC). Objective: To assess the impact of venous extension and wall invasion in RCC on survival. Design, setting, and participants: Data for 1023 RCC patients with vena cava thrombus treated with radical nephrectomy and complete tumor thrombectomy were collected within a prospectively maintained international consortium (1995-2012). Outcome measurements and statistical analysis: The Kaplan-Meier method and univariable and multivariable Cox regression analyses were used to assess the impact of MVI on cancer-specific survival (CSS). The main two variables of interest were microscopic renal vein wall invasion (MRVI) and microscopic vena cava wall invasion (MVCI). Results: MRVI was found in 725 cases (70.9%) and MVCI in 230 (22.5%). Patients with MRVI had larger tumors (p = 0.005), longer hospital stay (p< 0.001), higher clinical stage 0.039), higher Fuhrman grade (p = 0.028), and more frequent fat invasion. Presence of MVCI was associated with larger tumors (p< 0.001), longer hospital stay (p< 0.001), higher clinical stage (p< 0.001), lymph node involvement (p = 0.045), higher Fuhrman grade (p< 0.001), and higher thrombus level (p< 0.001). With median follow-up of 52 mo, overall 5-yr CSS was 57.4%. Multivariable analysis showed that presence of MRVI was an independent factor related to CSS (hazard ratio 2.24, 95% confidence interval 1.24-3.59, p = 0.006). The main limitation was the inability to report MVI percentages. Conclusions: Patients with MRVI experience significantly worse survival outcomes after radical nephrectomy and tumor thrombectomy. Consideration of MRVI at final pathology is appropriate to improve decision-making for risk-adapted follow-up. Patient summary: The behavior of locally advanced renal cell carcinoma (RCC) depends on clinical and pathologic factors. Analysis revealed that RCC patients with microscopic renal vein wall invasion experience significantly worse cancer-specific survival. Patients with microscopic renal vein invasion (MRVI) who undergo radical nephrectomy and tumor thrombectomy experience significantly worse cancer-specific survival than patients without MRVI. The presence of MRVI at final pathology should be taken into consideration to improve decision-making for risk-adapted follow-up.