Wilms tumor

Wilms tumor comes from immature cells in the kidney that grow out of control. For the large majority of children with Wilms tumor, the cancer happens randomly, but genetic causes can be found for a few children. Often, a Wilms tumor may be very large when it is found, even without the child feeling sick. Wilms tumor can sometimes spread (metastasize) to another part of the body such as the lungs or the liver. The average age at diagnosis is 3 years, and nearly all children with Wilms tumor are age 7 years or younger.