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Wilms Tumor

  • Amy Scholten, MPH
Publication Type:


Wilms Tumor

(Nephroblastoma; Kidney Tumor)


Wilms tumor is a rare type of kidney cancer. It is mainly found in children. It is often cured with treatment.

The Kidneys

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Before birth, some kidney cells do not grow the way they should. 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

Wilms tumor affects children 0 to 4 years old. Things that raise the risk are:

  • An abnormal gene passed down from a parent
  • A family history of Wilms tumor
  • Certain syndromes, gene defects, and birth abnormalities that may cause:
    • The colored part of the eye to be missing
    • Genital abnormalities
    • Delayed development

Many children with Wilms tumors do not 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 symptoms may include:

  • Belly pain
  • Fever
  • Blood in the urine (pee)
  • Loss of hunger
  • Weight loss

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


The doctor will ask about the child’s symptoms and past health. During a physical exam, the doctor will look for signs of certain syndromes. These may point to a Wilms tumor.

To look for problems, tests will be done, such as:

The exam and test results will help find the stage of cancer. Wilms tumor is staged from 1 to 4. Stage 1 is a very localized cancer. Stage 4 has 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.

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

Chemotherapy uses drugs taken by mouth, shots, or IV to kill cancer cells. It may be used before surgery to shrink the tumor or after surgery to make sure all the cancer is killed. If the cancer comes back, stronger chemo may be used.

Radiation therapy may be used to kill cancer cells and shrink tumors after surgery. The radiation is aimed at a tumor from a source outside the body. It may be used for cancer that has spread or comes back.


Those with a family history of Wilms tumor may consider:

  • Gene testing before a pregnancy
  • Prenatal testing—to help find tumors early




  • Pater L, Melchior P, et al. Wilms tumor. Pediatr Blood Cancer. 2021;68 Suppl 2:e28257.
  • Wilms tumor. EBSCO DynaMed website. Available at:
  • Wilms tumor. Kids Health—Nemours Foundation website. Available at:
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.