Pediatric Wilms Tumor (Nephroblastoma)

Wilms tumor is a type of kidney cancer that requires high-level surgical expertise to treat. The physicians and surgeons at Children’s Health℠ have specialized training and expertise in treating children with Wilms tumor. We offer the latest therapies and surgical approaches, to give your child the best opportunity for a long, healthy life.

What is a Pediatric Wilms Tumor?

Wilms tumors are a type of kidney cancer that primarily affects children. Wilms tumor is the most common type of pediatric kidney cancer. These tumors usually occur before age 5 and are almost always detected by age 10.

Most children have one tumor in one kidney, but a small number of children develop multiple tumors in one or both kidneys. Wilms tumor is also called nephroblastoma.

What are the different types of Pediatric Wilms Tumors?

Doctors classify Wilms tumors based on how cancer cells look under a microscope. The two types of Wilms tumors are:

Favorable histology

These cancer cells look more like healthy cells than diseased ones. Nearly 90% of Wilms tumors have a favorable histology. This type is easier to treat and cure.

Anaplastic histology

Anaplastic cells look very different from healthy cells because their central parts, which contain DNA, are enlarged and distorted. This condition is called anaplasia. Diffuse anaplasia, or distortion throughout a tumor, is harder to treat than focal anaplasia, which is distortion found in just one part of the tumor.

What are the signs and symptoms of Pediatric Wilms Tumors?

Wilms tumors can grow fairly large before you or your child notice symptoms. One of the first signs is abdominal swelling. Your child’s belly may look bloated or you might feel a hard lump when you press on the stomach. Some children have abdominal pain.

Other symptoms include:

How is a Pediatric Wilms Tumor diagnosed?

We may use one or more of the following tests to diagnose a Wilms tumor:

Blood test

Measure blood cell counts


Assess kidney function

CT scan (computed tomography)

To view cross-sectional images of organs and detect kidney tumors

Magnetic Resonance Imaging (MRI)

To get detailed 3D images of organs and surrounding soft tissues. MRIs can help determine if a cancer has spread.


To view the kidney in 3D and look for tumors

What causes Wilms Tumors in children?

Most children develop Wilms tumors for no apparent reason. The disease is slightly more common in girls and black children. Any child can get these tumors, but these factors increase their risk:

Birth defects

An estimated one out of every 10 children with Wilms tumors also has a genetic condition present at birth (a birth defect). Certain pediatric chromosomal abnormalities and tumor-causing conditions like Beckwith-Wiedemann syndrome increase a child’s chances of Wilms tumors.

Family history

Certain gene changes (genetic mutations) may slightly increase Wilms tumor risk. Up to 2% of children with Wilms tumors have a relative with the same cancer.

How are Pediatric Wilms Tumors treated?

Surgery (nephrectomy)

Kidney surgery (nephrectomy) is the best way to treat Wilms tumors.

Radical nephrectomy

We remove the entire kidney and tumor along with some nearby glands and fatty tissue. This approach ensures that none of the cancerous tissue remains. Having just one kidney shouldn’t affect your child’s health or lifespan.

Partial nephrectomy (kidney-sparing surgery)

If both kidneys have tumors, we remove just the tumors and some of the surrounding tissue. The remaining kidney works almost as efficiently as a whole kidney and shouldn’t affect your child’s health or quality of life.

Follow up


We may give chemotherapy before surgery to destroy the cancer cells and shrink the tumor (called neoadjuvant chemotherapy) or after surgery to get rid of lingering cancer cells.

Radiation therapy

We may recommend using high-energy radiation beams to destroy cancer cells as part of the initial treatment of some Wilms tumor or in the rare cases where the tumor returns after treatment.

Why Children's Health?

At Children's Health, the surgeons are also faculty members at UT Southwestern Medical Center. They see more children with Wilms tumors than almost any other cancer center in the country. This gives them the experience to identify the surgical approach that is right for your child, and to make surgery as successful as possible. Your child’s care team may include:

Pediatric Wilms Tumor (Nephroblastoma) Doctors and Providers

Our genitourinary tumor team brings together top cancer specialists to treat children with Wilms tumors.

Frequently Asked Questions

  • How common is kidney cancer in children?

    Kidney cancer is much more common in adults than children. Between 450 and 500 children have a Wilms tumor diagnosis every year.

  • Is a Wilms Tumor curable?

    With proper treatment, the survival rate for children with Wilms tumors is as high as 90%. However, there is a chance that cancer will come back, usually within two years after your child finishes treatment.

    We continue to monitor your child’s health after treatment to detect cancer recurrence quickly, so we can restart treatment as soon as possible. A reappearing Wilms tumor may affect the kidneys or another organ, such as the lungs.

  • What are the stages of Wilms tumors?

    Cancer stages reflect how far cancer cells spread from their original location. Our doctors rely on cancer staging to guide treatment decisions. The same tests used to diagnose Wilms tumor can determine the cancer’s stage. Your child shouldn’t need additional tests.

    Wilms tumor cancer stages range from one to five:

    • Stage 1: Tumor is limited to one kidney with no evidence of spread outside of that kidney
    • Stage 2: Tumor has grown outside of the kidney into nearby fatty tissue or blood vessels but no further
    • Stage 3:Tumor is present in the lymph nodes at diagnosis or the tumor capsule has ruptured
    • Stage 4: Cancer has spread to other organs outside of the kidney at diagnosis. This is most commonly in the lungs, but rarely may include the liver or bones.
    • Stage 5: One or more Wilms tumors are in both kidneys
  • What other factors are used to determine the best treatment for Wilms tumor?

    Other factors – outside of the stage of the tumor – also impact treatment decisions. Whether a Wilms tumor is determined to have a “favorable histology” or “anaplastic histology” is probably the single most important factor, with anaplastic Wilms tumor requiring more aggressive treatment.

    More recent research has demonstrated the impact of certain genetic changes in some Wilms tumors on the outcome. We use this genetic data to identify Wilms tumor at higher risk of recurrence and change the treatment, so that we can provide tailored therapy for each Wilms tumor.