Pediatric urologic oncology

Abstract

Wilms' tumor is the most common malignant neoplasm in the urinary tract of children. More than 500 new cases occur annually in the United States. The incidence of Wilms' tumor has remained relatively constant at 7.8 per million children per year. Recent advances in chromosomal and biochemical analysis have made it possible to identify persons at higher risk for development of Wilms' tumor. The tumor appears to occur in either heritable or nonheritable form. In children with the heritable form, the neoplasm develops at an earlier age and is more likely to be bilateral and multicentric. All bilateral cases and from 15 to 20 per cent of unilateral Wilms' tumors may be attributable to the heritable form of disease. Significant associations with aniridia, hemihypertrophy, and congenital urinary tract defects have been well documented. Genitourinary anomalies (renal hypoplasia, fusion anomalies, renal ectopy, duplication, hypospadias, and cryptorchidism) are present in 4.5 per cent of patients with Wilms' tumor. Hemihypertrophy occurs in 2.9 per cent of patients. Aniridia occurred in 1.1 per cent of 547 patients with Wilms' tumor evaluated by the National Wilms' Tumor Study Group. Chromosomal analysis by high-resolution banding has demonstrated that the complex of Wilms' tumor and aniridia is associated with a chromosomal deletion at 11p13. In addition, these patients have a significant reduction in the level of the enzyme catalase. Reduced levels of catalase may provide an additional marker for an 11p13 deletion and thereby identify patients with aniridia who are at increased risk for the development of Wilms' tumor.