Tumor thrombus and microvascular invasion as prognostic factors in renal cell carcinoma

The significance of two types of vascular invasion (macroscopic tumor thrombus into the renal vein or vena cava inferior and microvascular invasion) as prognostic factors in renal cell carcinoma is analyzed in 121 patients treated at the Department of Urology, Nara Medical University. The data indicate there to be close correlations between tumor thrombus, microvascular invasion and distant metastasis. In patients with tumor thrombus, however, the prognosis is not as poor when surgical removal of the tumor thrombus is successfully performed as when it is not. In contrast, the prognosis of patients with positive microvascular invasion is significantly worse than that of those with a negative finding. Microvascular invasion appears to be a significant prognostic factor in renal cell carcinoma in addition to well-known factors such as tumor stage, tumor grade, tumor thrombus and distant metastasis. To detect microvascular invasion, the histological examination should be extended to give as much detail as possible.