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Wilms Tumor




Wilms tumor is also called nephroblastoma.

This is the fourth most common form of childhood cancer and the most common primary renal tumor in children (6% of all childhood cancer).


Summary of Wilms Epidemiology:

Annual incidence

(In patients <16 years)

7 per million children

Proportion of pediatric cancers


Age affected

Mostly <5 years old

  • 0.16% occur in neonates
  • 50% are less than 3 years old
  • 90% are less than 7 years old
  • Extremely rare over the age of 15


Sporadic cases with unilateral tumors present at an older age (median 36 months) than familial synchronous bilateral Wilms tumor (median age 26 months).


Proportion of patients with various anomalies

Musculoskeletal: 2.9%
Genitourinary: 4.4%


Peak incidence

3-4 years

Median age at diagnosis is 3.5 years


Gender bias

Generally female predominance for both unilateral and bilateral tumors.

  • The male to female ratio is 0.92 for unilateral tumors.
  • The male to female ratio is 0.6 for bilateral tumors.
  • In South East Asia excess of cases in males.


Wilms tumor was first described in detail by Max Wilms. There is a brief biography on the National Wilms Tumor Study website:




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