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Quick Facts

Wilms Tumor


The Manual's Editorial Staff

Last full review/revision Sep 2020| Content last modified Sep 2020
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What is Wilms tumor?

Wilms tumor is a type of cancer in which a tumor grows on a kidney. It happens most often in children younger than 5.

  • Doctors don’t know what causes Wilms tumor, but children who have certain health problems at birth are more likely to get it

  • Children with Wilms tumor have a lump in their belly and may throw up and have belly pain, fever, poor appetite, and upset stomach

  • Wilms tumor usually affects one kidney, but it can affect both

  • Treatment includes surgery, chemotherapy, and sometimes radiation therapy

What causes Wilms tumor?

Most of the time, doctors don’t know what causes Wilms tumor. Sometimes it's caused by a problem with the child's genes.

What are the symptoms of Wilms tumor?

The first symptom of Wilms tumor is usually:

  • A painless lump in a child's belly

Other symptoms include:

  • A swollen belly (sometimes parents notice that a young child suddenly needs a larger-sized diaper)

  • Belly pain, fever, poor appetite, upset stomach, and throwing up

  • Blood in the urine

  • High blood pressure

If the cancer spreads to the lungs, it may cause coughing and shortness of breath.

How can doctors tell if my child has Wilms tumor?

Doctors suspect Wilms tumor if they feel a lump in a child's belly. To know for sure, they'll do:

  • Ultrasonography, CT scan, or MRI

  • Surgery to remove the lump—doctors will look at it under a microscope to see if it's Wilms tumor

Doctors also use CT scan or MRI to see if any cancer has spread to the lymph nodes, liver, or lungs.

How do doctors treat Wilms tumor?

To treat Wilms tumor, doctors will:

  • Do surgery to remove the kidney that has the tumor

  • During surgery, check the other kidney for cancer

  • After surgery, treat the child with chemotherapy

  • If the cancer has spread, do radiation therapy

In rare cases where a tumor is very large or is in both kidneys, doctors will use chemotherapy to shrink the tumor or tumors before doing surgery to remove them.

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