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Approximately 550 children and adolescents
are diagnosed with renal tumors in the United States each year.
The vast majority of these (about 500 cases yearly) are nephroblastomas,
also known as Wilms tumors (WT). Other types of renal tumors of
childhood include rhabdoid tumor of the kidney (RTK), clear cell
sarcoma (CCS), renal cell carcinoma (RCC), and congenital mesoblastic
nephroma (CMN). The relative incidence of each tumor is presented
in eTable 456.1. It is important to note
that the incidence of the tumor type varies with the age of the
patient. Wilms tumors account for 95% of renal tumors of
childhood, whereas adolescents over 15 years of age are more likely
to be diagnosed with RCC than WT (incidence RCC .07 versus WT .04
in adolescent patients). A renal mass in an infant less than 3 months
of age is likely to be a congenital mesoblastic nephroma, or rhabdoid
tumor. Still, the overall incidence of each of these other renal
tumors of childhood (CCS, RTK, CMN) is quite low. Therefore, this
chapter will focus primarily on WT as the major renal tumor of childhood.
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Clinical research in pediatric renal tumors is an exemplary
model of how national and international collaborative studies have
been able to make marked improvements in outcome over time. Coordination of multimodal therapy for patients with
WT has resulted in improvement in overall survival from a nearly
uniformly lethal disease in the early 1900s, to approximately 30% in
the 1930s, to nearly 90% in the early 21st century. This
progress has been largely due to the efforts of several groups,
including the National Wilms Tumor Study Group (NWTS) in North America
and the International Society of Pediatric Oncology (SIOP) in Europe.
Five major studies have been conducted in North America by the NWTS,
each providing valuable clinical information to help ...