Wilms' Tumor

Written by Jaime Herndon | Published on August 7, 2012
Medically Reviewed by Brenda B. Spriggs, MD, MPH, FACP on August 7, 2012

What is Wilms Tumor?

Wilms tumor is the most common type of kidney cancer in children. According to St. Jude Children’s Research Hospital, it is the fourth most common type of childhood cancer, with approximately 460 new diagnoses made each year in the United States (St. Jude).

Cancer occurs when abnormal cells in your body multiply uncontrollably. This can happen at any age, but some cancers are unique to childhood and Wilms tumor or nephroblastoma, as it is also known, is one such cancer.

Wilms is a solid tumor of the kidneys. It is typically diagnosed around 3 years of age, with boys and girls being equally affected. It is rarely seen or diagnosed after the age of 8.

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What Causes Wilms Tumor?

In most cases, Wilms tumor cannot be linked to a specific cause. Studies are under way to determine whether environmental factors, such as drugs, chemicals, or infectious agents, can cause Wilms tumor.

Some children have genetic factors that increase their risk of developing the disease, including certain syndromes that are associated with Wilms tumor. One such condition is Beckwith-Wiedemann syndrome, which is a growth disorder that causes body and organ enlargement. Other abnormalities associated with this cancer include a missing iris in the eye and the enlargement of one side of the body.

About 1.5 percent of children with this cancer have a relative who is also affected by the disease. Siblings and twins are also more commonly diagnosed, which point to genetic factors as a cause of the cancer.

What Are the Signs and Symptoms of Wilms Tumor?

Symptoms of Wilms tumor are similar to those of other childhood ailments, so it is important to see your doctor for an accurate diagnosis. Children with Wilms tumor might display the following symptoms:

  • constipation
  • abdominal pain, swelling, or discomfort
  • nausea
  • loss of appetite
  • fever
  • blood in the urine or discoloration of urine
  • high blood pressure
  • increase and uneven growth of one side of body

How Is Wilms Tumor Diagnosed?


The doctor will do a physical examination of your child and record a family history. He or she may also order diagnostic tests, including:

  • blood tests to determine kidney function (urinalysis, blood urea nitrogen, creatinine, and creatinine clearance)
  • complete blood count
  • an abdominal X-ray or ultrasound
  • a CT scan

These tests will help your doctor make an accurate diagnosis. Once diagnosed, more tests will be done to determine how advanced the disease is. Treatment and prognosis will depend on the stage of the cancer.


Wilms tumor is staged using the Roman numerals I through V:

  • Stage I: The tumor is contained within one kidney and can be completely removed with surgery; 40 to 45 percent of Wilms tumors are stage I.
  • Stage II: The tumor has spread into the tissue and vessels around the kidney, but can still be completely removed with surgery; 20 to 25 percent of Wilms tumors are stage II.
  • Stage III: The tumor cannot be completely removed with surgery, and some cancer remains in the abdomen; 20 to 25 percent of Wilms tumors are stage III.
  • Stage IV: The cancer has spread to faraway organs, such as the lungs, liver, or brain; 10 percent of Wilms tumors are stage IV.
  • Stage V: The tumor is in both kidneys at the time of diagnosis. If both kidneys must be removed, the child will need dialysis and a kidney transplant; 5 percent of Wilms tumors are stage V.

Treatment and Outlook for Wilms Tumor

Most children undergo a combination of treatments, including surgery, chemotherapy, and radiation therapy. These treatments achieve cure rates of between 85 and 90 percent. The specific drugs and the extent of treatment will vary among individual children.

Complications from Wilms Tumor

As with any cancer, metastasis, or spreading of disease to other organs, is a potentially serious complication. If the cancer spreads to distant organs, it will require more aggressive treatment.

High blood pressure and kidney damage can occur as a result of the tumor or its treatment. Depending on the drugs used for chemotherapy, you may also experience unpleasant side effects, such as hair loss, nausea, and fatigue. Ask your doctor about each medication prescribed for this condition and ask about what to expect during and after treatment.

Can Wilms Tumor Be Prevented?

Wilms tumor cannot be prevented. For children with a family history of the condition, frequent kidney ultrasounds are a beneficial screening tool to ensure early detection.

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