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 to is the lungs. But it may also spread to the liver, lymph nodes, other kidney, brain, and bones.

For more information regarding Wilms tumor services in St. Louis, please call 314.454.5437 or 800.678.5437 or email us.


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.

Risk Factors

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.


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)

Many of these symptoms may be caused by other health problems. But it is important to see your child's healthcare provider if you notice these symptoms. Only a healthcare provider can tell if your child has cancer.


If your child's healthcare provider thinks your child might have Wilms tumor, certain exams and tests will be needed to be sure. 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 belly.
  • 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 much 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 show 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 nearby 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 how well the kidneys and liver are working 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 size and location of the tumor 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 take out 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 checked for signs of cancer.
  • 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. Cancer treatment can cause side effects. Medicines and other treatments can be used to help ease side effects such as pain, fever, infection, and nausea and vomiting.
  • Clinical trials. Ask your child's healthcare provider if there are any new 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 outcomes. 
  • Ongoing follow-up care during and after treatment is needed.
  • New treatments are being tested to improve outcomes and to lessen side effects.
You can ask your child's healthcare provider about survival rates and what you might expect. But remember that statistics are based on large groups of people. They can't be used to say what will happen to your child.


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

Your child's care team will review what complications you need to consider based on your child's specific treatment plan.

For more information regarding Wilms tumor services in St. Louis, please call 314.454.5437 or 800.678.5437 or email us.

Living with

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

  • Learn as much as you can about Wilms tumor. This can help you make the best decisions for your child.
  • Get emotional support for your child. Finding a counselor or child support group can help.
  • Make sure your child gets to all appointments and treatment visits.
  • 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.

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 to Call a Healthcare Provider

Call the healthcare provider if your child has:

  • Symptoms that get worse
  • New symptoms
  • Side effects from treatment
Be sure to ask the healthcare provider about any problems or changes you should watch for and what you should do if you notice them.

Key Points

  • 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:
  • Know the reason for the visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.
  • Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
  • Ask if your child’s condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if your child does not take the medicine or have the test or procedure.
  • 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.

For more information regarding Wilms tumor services in St. Louis, please call 314.454.5437 or 800.678.5437 or email us.