When Your Child Has Wilms Tumor

Outline of small child showing lungs, kidneys, and ureters connecting kidneys to bladder.

Your child has been diagnosed with Wilms tumor. You are likely feeling shocked and scared. You are not alone. Support and treatment are available. Your child’s healthcare team will guide you through important decisions about your child’s health.

What is Wilms tumor?

Wilms tumor is a type of cancer that forms in the kidney. The kidneys are a pair of organs in the lower back on each side of the spine. They filter the blood by taking out the waste and water. The waste and water leave the body as urine. Wilms tumor usually affects one kidney, but can affect both. The tumor can spread (metastasize) to another part of the body, such as the lungs.

Who gets Wilms tumor?

Children at any age can get Wilms tumor, but kids under the age of 5 are affected most often. Wilms tumor is not contagious. This means that your child can’t pass it to another person. 

What causes Wilms tumor?

Wilms tumor occurs because abnormal cells grow in the kidney. These cells then form a tumor. What causes the abnormal growth of cells is not fully known. However, certain genetic diseases, conditions, and birth defects have been shown to increase a child’s risk of Wilms tumor. Your child’s healthcare provider may be able to tell you more.

What are the symptoms of Wilms tumor?

Some common symptoms of Wilms tumor include a lump in the stomach, pain and swelling in the stomach, and blood in the urine. Appetite loss, fever, headache, and weight loss are also possible. Your child may have experienced some of these symptoms, or other symptoms.

How is Wilms tumor diagnosed?

Your child’s healthcare provider examines your child. You will be asked about your child’s health history. Your child may also have one or more of the following:

  • Blood and urine tests to  look at blood counts and see how well certain organs are working.

  • Imaging tests to take detailed images of areas inside the body. These may include X-ray, computed tomography (CT) scan, or ultrasound.

  • Surgery to take out the tumor and see if it is cancerous.


Staging and grading of Wilms tumor

Staging is the process that tells the size of the cancer and how much it has spread. Your child's healthcare provider uses exams and tests to find out the size of the cancer and where it is. He or she can also see if the cancer has grown into nearby areas, and if it has spread to other parts of your child's body. 

Grading is used to describe how abnormal the cancer cells look when seen through a microscope. The more abnormal the cells are, the faster they grow. Staging and grading help the healthcare team plan treatment for your child. They also help determine the likelihood of cure (prognosis). The process used for Wilms tumor takes into consideration the following:

  • Location of the primary tumor

  • If the tumor has spread outside of the kidney to nearby tissues

  • If the cancer has spread to the other kidney or other parts of the body

  • How abnormal the cancer cells look under a microscope

The Children's Oncology Group staging system is commonly used to stage Wilms tumors. The stages are written as Roman numerals and can have a value of I through V (1 through 5). The different stage numbers refer to the tumor’s size and if and where it has spread. For instance, stage I is an early stage of cancer, the tumor is only in the kidney where it started and all of the tumor was removed with surgery. Stage V means the cancer is in both kidneys when it's first diagnosed. Your child’s healthcare provider can tell you more if needed. Talk with your child's healthcare provider if you have any questions about the stage of your child’s cancer.

How is Wilms tumor treated?

The goal of treatment is to destroy the cancer cells. The kind of treatment used depends on the type and stage of tumor your child has. Your child may require one or more of these treatments:

  • Surgery to remove the kidney where the tumor is (called a nephrectomy) or to remove as much tumor as possible from the remaining kidney if one was already removed.

  • Chemotherapy (“chemo”) to destroy cancer cells with powerful cancer-fighting medicines. Your child may receive a combination of medicines. They are given through a small tube (IV) that’s usually put into a vein in the arm or chest. Or, they may be given by mouth or injection.

  • Radiation therapy to destroy cancer cells and shrink a tumor using strong X-rays. Radiation may be used before or after other treatments.

Supportive treatments

Supportive treatments help to protect the child from infection, prevent discomfort, and bring the body’s blood counts back to a healthy range. During your child’s treatment, he or she may be given antibiotics. These are medicines that help prevent and fight infection. Other medicines may also be given. These help ease the side effects caused by treatment, such as nausea. Your child may also get a blood transfusion to restore the blood cells. The blood cells cannot grow because of the effects of treatment. For the blood transfusion, blood is taken from a donor and stored until the child is ready to get it.

What are the long-term concerns?

With early treatment, Wilms tumor is usually curable. But chemotherapy and radiation may cause some problems, such as damage to certain organs. So your child’s health will need to be watched closely for life. This may include clinic visits, blood tests, and imaging tests. Also, ask your healthcare team if your child will need to take special safety measures to protect the remaining kidney, such as avoiding contact sports.


Getting a cancer diagnosis for your child is scary and confusing. Remember that you are not alone. Your child’s healthcare team will help guide you and your child throughout your child’s illness and care. You may also want to seek information and support for yourself. Doing so helps you cope with the changes cancer brings. Learning about your child's cancer and talking with others who also have a child with cancer may help you and your family cope with the changes cancer brings. Also, ask your child’s healthcare team for a list of resources.