Renal tumors in children aged 10-16 Years: a report from the United Kingdom Children's Cancer and Leukaemia Group.

Wilms tumor is the most common renal tumor of childhood. However, other epithelial, mesenchymal, and neuroectodermal neoplasms may also arise in the kidney during childhood, several of which show specific age distributions; in the 1st year of life, mesoblastic nephroma and rhabdoid tumor are more common, whereas renal cell carcinoma, primitive neuroectodermal tumor, and anaplastic Wilms tumors are relatively more frequent in older children and adolescents. The aim of this study is to describe the spectrum of renal tumors in children aged 10-16 years using data from 1492 patients registered in the UK Wilms Tumour 3 Trial (1991-2001) and International Society of Paediatric Oncology Wilms Tumour Trial 2001 (2002-2008) clinical trials of renal tumors in childhood. There were 67 (4.6%) tumors in children aged 10-16 years: 50 Wilms tumors (74.6%), 10 (14.9%) renal cell carcinomas, 3 (4.5%) renal medullary carcinomas, 2 (3%) primitive neuroectodermal tumors, 1 clear cell sarcoma of kidney, and 1 desmoplastic small round cell tumor. Fourteen percent of the Wilms tumors in this age group had diffuse anaplasia. Among the 10 renal cell carcinomas, 4 were associated with t(Xp-11.2), 3 were of papillary type II, 1 was papillary type I, 1 was clear cell type, and 1 was unclassified. Five-year overall survival for Wilms tumor was 63% (43% for anaplastic tumors), significantly lower than reported overall survival for all pediatric Wilms tumors. Only 40% of patients with renal cell carcinoma survived, and all patients with other tumors died.