Children - Wilms Tumor

What is Wilms tumor?

Wilms tumor is a cancerous tumor that starts in the cells of the kidney. It’s the most common type of kidney cancer in children. It’s usually found by the time a child is age 3 or 4. The tumor can be very large before it’s found. And it may spread (metastasize) to other body tissues. The most common site for Wilms tumor to spread is the lungs. But it may also spread to the liver, lymph nodes, other kidney, brain, and bones.

What causes Wilms tumor?

Most cases of Wilms tumor occur by chance with no clear cause. Defects in genes affect the growth of kidney cells. But it’s not common for Wilms tumor to run in families.

Who is at risk for Wilms tumor?

A small number of children with Wilms tumor also have a syndrome caused by abnormal genes, such as:

  • WAGR
  • Denys-Drash
  • Beckwith-Wiedemann

Some birth defects may increase the chance of Wilms tumor. For example, a boy with defects of the penis or testicle may be more at risk. Talk with your child's healthcare provider if you want more information about these conditions.

What are the symptoms of Wilms tumor?

Symptoms can occur a bit differently in each child. They can include:

  • A  lump in the belly (abdomen)
  • Swelling of the belly
  • Pain in the belly, but some children have no pain
  • Blood in the urine
  • Fever
  • High blood pressure (hypertension)

The symptoms of Wilms tumor can be like other health conditions. Make sure your child sees a healthcare provider for a diagnosis.

How is Wilms tumor diagnosed?

Your child's healthcare provider will ask about your child's health history and symptoms. He or she will examine your child.  Your child may have tests such as:

  • Abdominal ultrasound. This test uses sound waves and a computer to create pictures of blood vessels, tissues and organs. It can show the kidney, the tumor, and blood vessels of the kidney. It can also help show if there are any tumors in the other kidney or other parts of the abdomen.
  • Abdominal CT scan. This test uses a series of X-rays and a computer to make detailed images of the belly (abdomen). CT scans are more detailed than standard X-rays.
  • MRI. This test uses magnets, radio waves, and a computer to make detailed images of the body. MRI can determine if cancer has spread to other parts of the body (metastasized). It can also show if there are cancer cells in the lymph nodes or other organs. 
  • Chest X-ray. An X-ray is done with a small amount of radiation. It can show if there the cancer has spread to the lungs.
  • Blood and urine tests. These can check the kidneys and liver and check overall health.
  • Biopsy. A small piece of tissue is removed and checked with a microscope for cancer cells. Samples of the tumor, nearby lymph nodes, and other tissue may be taken. A biopsy can also show the type of tumor. A biopsy of kidney tissue may not be done with some tumors.


Most children with Wilms tumor can be cured. Treatment will depend on the stage and other factors. Your child will be treated by specialists with experience in treating Wilms tumor. They may include a pediatric surgeon and a pediatric cancer specialist (oncologist). The cancer can be treated with any of the below:

  • Surgery. This is done to remove the affected kidney (nephrectomy). Removing only part of the kidney is not advised for most children. Samples of the kidney that is removed are studied. Samples of nearby lymph nodes may also be taken and studied.
  • Chemotherapy. These are medicines that kill cancer cells. They are used to destroy cancer cells before or after surgery. They are also used to treat cancer that has spread or grows back.
  • Radiation therapy. These are high-energy X-rays or other types of radiation. Radiation is used to kill cancer cells or stop them from growing. It may be used to treat cancer that has spread or grows back.
  • Supportive care. Treatment can cause side effects. Medicines and other treatments can be used for pain, fever, infection, and nausea and vomiting.
  • Clinical trials. Ask your child's healthcare provider if there are any treatments being tested that may work well for your child. 

Your child will need follow-up care during and after treatment to:

  • Check on your child's response to the treatment
  • Manage the side effects of treatment
  • Look for returning or spreading cancer

Some treatments may be hard on your child, but they increase the chance of your child living a long time. Discuss the side effects of treatment with your child's healthcare provider.

With any cancer, how well a child is expected to recover (prognosis) varies. Keep in mind:

  • Getting medical treatment right away is important for the best prognosis. 
  • Ongoing follow-up care during and after treatment is needed.
  • New treatments are being tested to improve outcome and to lessen side effects.

What are possible complications of Wilms tumor?

Possible complications can include:

  • Side effects of chemotherapy or radiation therapy, such as heart failure or growth of a new type of cancer
  • Problems from surgery, such as bleeding or infection
  • Pregnancy problems in the future
  • Cancer that grows back or spreads
  • Death

How is Wilms tumor managed?

You can help your child manage his or her treatment in many ways. For example:

  • Your child may have trouble eating. A dietitian may be able to help.
  • Your child may be very tired. He or she will need to balance rest and activity. Encourage your child to get some exercise. This is good for overall health. And it may help to lessen tiredness.
  • If your child smokes, help him or her quit. If your child doesn’t smoke, make sure he or she knows the danger of smoking.
  • Get emotional support for your child. Find a counselor or child support group can help.
  • Make sure your child attends all follow-up appointments.

Your child may need to:

  • Be checked for Wilms tumor if he or she has a condition that increases the chance of developing Wilms tumor
  • Have genetic testing and counseling

When should I call my child’s healthcare provider?

Call the healthcare provider if your child has:

  • Symptoms that get worse
  • New symptoms
  • Side effects from treatment

Key points about Wilms tumor

  • Wilms tumor is cancer that starts in the cells of the kidney.
  • It’s most often found in children between ages of 3 and 4.
  • It may not cause any symptoms and may not be diagnosed until it’s large.
  • Surgery, chemotherapy, radiation therapy may be used to treat Wilms tumor.
  • Most children with Wilms tumor can be cured with treatment.

Next steps

Tips to help you get the most from a visit to your child’s healthcare provider:
  • Before your visit, write down questions you want answered.
  • At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you for your child.
  • If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.
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