What is Wilms tumor?

Wilms tumor is a rare pediatric kidney cancer that typically affects children under the age of 4. It most often occurs in just one kidney, though it can sometimes be found in both kidneys at the same time.

Symptoms and diagnosis

Recognizing the signs of Wilms tumor

This may include:

  • Belly swelling

  • Pain in the belly, but some children have no pain

  • Blood in the urine

  • Anemia

  • Fever

  • High blood pressure 

  • Loss of appetite

Wilms tumor diagnosis

Your child’s doctor will do a full physical exam and take a detailed medical history. Additional tests may include:


If your child has been diagnosed with Wilms tumor, the doctor will assign a stage. Staging helps determine the treatment options:

The cancer is found only in one kidney, is completely contained within the kidney and can be completely removed with surgery.

The cancer has spread to the tissues and structures beyond the affected kidney, but it can still be completely removed by surgery.

The cancer has spread beyond the stomach and cannot be completely removed by surgery.


How we treat Wilms tumor

Treatment involves a combination of surgery and chemotherapy. For patients with advanced disease, radiation therapy may be recommended.

Fighting pediatric cancer and blood disorders

Our UW Health Kids | Carbone Cancer Center specialists offer the most advanced treatment options. Our pediatric cancer and blood disorder experts are national research leaders. We test new therapies and continue to work on therapies for pediatric cancer and blood disorders. For many children with rare or hard-to-treat conditions, clinical trials provide new options.

Learn more about our clinical trials

Smiling child with sign reading UW Health Kids
UW Health Kids
Our pediatric experts have served the special needs of children for more than 100 years. We focus on each child’s unique needs and offer social and emotional support to help you and your child face even the most complex condition. Our long history includes the creation of medical advances that save lives around the world. Together, we get your child back to health and enjoying being a kid.

Meet our team

Your child is in capable hands

Your child’s care is our top priority and we understand the unique needs they have. Your child’s team will include:

  • Oncologists (cancer doctors)

  • Hematologists (blood disease doctors)

  • Nurse practitioners

  • Child Life specialists

  • Pain management specialists

  • Physical, occupational and speech therapists

  • Radiologists and radiation technologists

  • Social workers

  • Surgeons

UW Health Kids | Carbone Cancer Center specialists are dedicated to diagnosing and treating all infants, children and adolescents with cancer, including rare cancers such as Wilms tumor.

Our pediatric oncologists are part of the UW Carbone Cancer Center which is a National Cancer Institute-designated Comprehensive Cancer Center. This designation means that the doctors taking care of your child are experts in cancer treatment, research and education. 

Pediatric hematology and oncology
Pediatric surgery
Radiation oncology
Pediatric urology


Care for your child

American Family Children’s Hospital

Receiving care from the pediatric hematology, oncology and bone marrow transplant program at American Family Children’s Hospital means you have access to the knowledge and skills of many medical and support specialists for your child’s complex health diagnosis like cancer.

Patient and support services

You’re never alone

When your child needs hospitalization, they will be admitted to American Family Children's Hospital in Madison, Wis.

Child life specialists help your child and family cope with any fears and anxieties. The American Family Children's Hospital patient and family visitor guide features information about:

  • Hero beads

  • Hospital school

  • Positive Image Center

  • Restoring Hope Transplant House (for blood and bone marrow transplant)

  • Spiritual care services

  • Tyler's Place (sibling child care)

Additional resources

Pediatric cancer services

With our expertise comes compassion. Our team considers you and your child part of our family. We will be by your side every step of the way. From diagnosis through treatment and into adulthood, we will care for your child as if they are our own.

Learn more