ABSTRACT
Incidence and Epidemiology Wilms’ tumor is one of the most common primary malignant tumors of childhood and also the most common renal tumor, accounting for 6% of all pediatric malignancy ( 1 , 2 ). It occurs mainly in young children with a mean age at diagnosis of three to four years (2) and 95% are diagnosed by the age of 10 years (1) . There is an equal distribution between the sexes (3) . In Europe the incidence is 10/1,000,000 per year with approximately 900 cases diagnosed each year (2) . The incidence has remained relatively constant and therefore was once considered an “index” tumor of childhood. However, there are variations according to ethnicity, with higher rates reported in the Afro-Caribbean population (9-12/1,000,000) than in Caucasians (6-10/1,000,000) and the lowest rates reported among East-Asians (3/1,000,000) (4) . These variations are ethnic rather than geographical, suggesting that environmental factors do not play an important role. The role of environmental exposures in utero as a cause of early onset of Wilms’ tumor in infancy remains unproven (5) .
