Capsular and vascular invasion: important prognostic factors in Wilms' tumor.

The influence of capsular and vascular invasion on prognosis was determined retrospectively in 52 children with Wilms' tumor. Local recurrence was more prevalent (0.26) in patients with rupture or capsular invasion than in any other group. Inadequate postnephrectomy irradiation or infiltration of the liver by nephroblastoma cells appeared to be predisposing factors in the development of these reccurrences. Of the 26 patients with gross or microscopic vascular invasion, 13 developed metastasis. This proportion was significantly higher than in patients without vascular involvement (p less than 0.05). These observations emphasize the importance of microscopic detection of capsular and vascular invasion in staging of Wilm's tumor.