Does left side renal cell carcinoma (RCC) with renal vein/vena cava thrombus predict worse prognosis than equivalent right side RCC tumor thrombus?

Purpose To determine whether renal cell carcinoma (RCC) thrombi that reach the vena cava from the left kidney are associated with a greater risk of RCC death than equivalent thrombi from the right kidney. Methods: Two hundred and fifty-nine patients treated with radical nephrectomy (1970-2006) for unilateral, sporadic RCC with level 1-4 RCC tumor thrombus were identified. Clinicopathologic features between patients with right-sided (N = 183) and left-sided (N = 76) thrombus were compared utilizing Wilcoxon rank sum and Fisher's exact tests. Associations with RCC-specific death using hazard ratios (HR) and 95 % confidence intervals (CIs) from Cox proportional hazards models were evaluated. Results: Left-sided RCC patients with thrombus are less likely to be clear cell subtype (85 % vs. 93 %; p = 0.013) and more likely to have nodal involvement (28 % vs. 16 %; p = 0.018) compared to right side RCC patients with thrombus. Overall, there is little evidence that the risk of RCC death is higher for left versus right-sided RCC thrombus (HR = 1.11; 95 % CI 0.81-1.53; p = 0.52). However, among those patients with a thrombus that has reached the vena cava (level III/IV), we observe evidence after multivariate adjustment that the risk of RCC death is higher for left versus right side patients (HR = 2.02; 95 %CI 0.91-4.47; p = 0.08). Conclusions Left side RCC with tumor thrombus is not associated with worse prognosis than right-sided tumors (all tumor thrombi levels). Our data suggest that among RCC patients with advanced tumor thrombi (level III/IV), a left side thrombus may be associated with worse prognosis compared to a right side thrombus.