by EBSCO Medical Review Board
(Nephroblastoma; Kidney Tumor)


Wilms tumor is a type of kidney cancer . It’s mainly found in children. Most of the time, it’s found in one kidney, not both.

The Kidneys
Copyright © Nucleus Medical Media, Inc.


Before birth, some of kidney cells don’t mature like they’re supposed to. After the baby is born, clusters of these cells are still there. If they do not mature within 3 to 4 years, they may grow without control or order. A large mass of these cells may grow into a Wilms tumor.

Risk Factors

The chances of Wilms tumor are higher for:

  • Getting a certain gene from a parent that isn’t normal
  • Having someone in the family with same problems
  • Certain syndromes such as:
    • WAGR—a syndrome that includes:
      • W ilms tumor
      • A niridia—The colored part of the eye may be partly or fully missing.
      • G enitourinary abnormalities
      • R etardation
    • Beckwith-Wiedemann syndrome—Larger than normal tongue and organs. One arm or leg may be larger than the other.
    • Perlman syndrome—Large size before birth. May also have Wilms tumor. These may involve other organs and intellectual problems.
    • Denys-Drash syndrome—Male genitals are not present or completely formed.
    • Hemihypertrophy—One side of the body larger is than the other.
    • Other defects on chromosome 11.

Many children with Wilms tumors don’t have these problems. The cause of their kidney cells not maturing is unknown.


Wilms tumor may be first felt as a large mass in the belly. Other problems may include:

  • Stomach pain
  • Fever
  • Blood in the urine
  • Loss of hunger

Wilms tumors may grow larger without causing pain or other problems.


You will be asked about your child’s symptoms and health history. During a physical exam, the doctor will look for signs of the syndromes listed above. These may point to a Wilms tumor.

The exam and test results will help find out the stage of cancer. Staging helps with planning. Wilms tumor is staged from 1-4. Stage 1 is a very localized cancer. Stage 4 is a spread to other parts of the body.


Wilms tumor can be cured in most children. The plan depends on the stage of cancer. Many times, different methods are used. These may include:


Surgery is done to remove as much cancer as possible. Nearby lymph nodes or other sites with cancer will also be removed. A nephrectomy may be:

  • Partial—removal of the cancerous part of the kidney to treat smaller tumors that have not spread
  • Radical—removal of the entire kidney and other nearby structures


Chemotherapy is the use of drugs to kill cancer cells. It may given by mouth, shots, or IV. The drugs enter the bloodstream and travel throughout the body.

Radiation Therapy

This is the use of radiation to kill cancer cells and shrink tumors after surgery. External radiation therapy is aimed at a tumor from a source outside the body.


If you have Wilms tumor in your family, talk to your doctor about genetic testing before you start your own family. If your child is at high risk, talk to their doctor about screening. This may help find tumors early.


American Cancer Society 

National Cancer Institute 


Childhood Cancer Canada 

Sick Kids—The Hospital for Sick Children 


Driskoll K, Isakoff M, Ferrer F. Update on pediatric genitourinary oncology. Curr Opin Urol. 2007;17(4):281-286.

Wilms tumor. EBSCO DynaMed website. Available at: Accessed January 29, 2021.

Wilms tumor. Kids Health—Nemours Foundation website. Available at: Accessed January 29, 2021.

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