Renal vein involvement with nephroblastoma: a report of the National Wilms' Tumor Study-3.

The records of children enrolled in the National Wilms' Tumor Study-3 who had Wilms' tumor and thrombosis into the renal vein were reviewed. There were 164 patients with gross involvement of the extrarenal vein and 47 patients with microscopic involvement, an incidence of 11.3% (211 of 1,865 evaluable patients). Two-year survival rates were 90, 79 and 72% for stages II, III and IV, respectively. The most important predictors of survival were histologic pattern and stage. Complete en bloc excision of the tumor and thrombus continues to be the most effective initial management.