Key Points about Wilms Tumor

  • If diagnosed early, Wilms tumor is reasonably treatable and most children with the condition go on to live healthy, everyday lives.
  • Doctors use imaging tests, physical exams and urinalysis to diagnose Wilms tumor.
  • Treatment for Wilms tumor may involve surgery, chemotherapy and/or radiation therapy.


Wilms tumor is a type of rare kidney cancer that primarily affects children. Wilms tumor is most common in children under the age of five but is diagnosed in kids before the age of 10. Also known as nephroblastoma, Wilms tumor can affect one or both kidneys at the same time. This type of cancer can spread to other parts of the body. There are two major types of Wilms tumor: favorable histology and anaplastic histology.

Wilms tumor causes

Experts haven’t yet pinpointed the exact cause of Wilms tumor. However, in some cases, it seems that genetics play a role. Particularly, Wilms tumor is associated with different gene mutations and several genetic conditions that share a genetic cause, including WAGR syndrome, Denys-Drash syndrome and Frasier syndrome. And nearly all cases of Wilms tumor affecting both kidneys are believed to be caused by immature kidney tissue that did not develop properly. 

Wilms tumor risk factors

The following factors may increase the risk for developing Wilms tumor:

  • Being African-American
  • Having aniridia (a condition in which the iris of the eye only partially forms)
  • Having Beckwith-Wiedemann syndrome
  • Having Denys-Drash syndrome
  • Having hemihypertrophy (one side of the body is noticeably larger than the other side)
  • Having WAGR syndrome

Wilms tumor symptoms

Wilms tumor often grows large before symptoms appear. The most common symptoms of Wilms tumors are:

  • A mass in the abdomen that can be felt
  • Pain in the abdomen
  • Swelling of the abdomen

Other, less common symptoms of this cancer can include:

  • Hematuria (blood in the urine)
  • Constipation
  • Decreased appetite
  • Fever
  • Hypertension (high blood pressure)
  • Nausea or vomiting
  • Shortness of breath

Wilms tumor diagnosis

Your child’s doctor may use one or more of the following tests to diagnose this condition:

  • Physical exam - your doctor will perform a complete physical exam – including asking questions about your child’s health history, their symptoms and related risk factors.
  • Blood tests - this test checks for unusual substances or levels in the blood, as well as for signs of how well the body is working.
  • Computerized tomography (CT) scan - your doctor may order a CT scan of your child’s kidney and surrounding areas. This specialized imaging test uses a series of X-ray images to create detailed images of the inside of their body.
  • Kidney biopsy - if imaging tests determine the presence of a tumor, doctors perform a biopsy to examine a tissue sample under a microscope.
  • Magnetic resonance imaging (MRI) - this type of imaging test uses radio waves and magnets to create detailed images of the inside of your child’s body.
  • Ultrasound - your doctor may order an ultrasound, an imaging test that uses sound waves to create detailed images of your child’s kidney and surrounding areas.
  • Urinalysis - this test checks for blood or other substances in the urine, as well as how well the kidneys are working.

Wilms tumor treatments

Depending on your child’s personal health history and other factors, your doctor may recommend one or more of the following treatment options:

  • Chemotherapy - this treatment involves the use of medications to destroy cancer cells. Chemotherapy drugs can be delivered via a pill taken orally (by mouth) or an intravenous liquid (injected into a vein).
  • Clinical trials - participation in clinical trials is one way to access newer treatments.
  • Immunotherapy - this is a treatment that uses your child’s immune system to fight cancer. 
  • Radiation therapy - during this treatment, your oncologist uses high-energy beams or rays to destroy cancerous cells. 
  • Surgery - this treatment involves removing the cancerous cells during a surgical procedure. Your surgeon aims to leave as much healthy kidney tissue intact as possible. In a partial nephrectomy, your child’s surgeon removes the tumor and a small part of surrounding kidney tissue. In a radical nephrectomy, your child’s surgeon removes the entire affected kidney and some surrounding tissue. 

When should I seek care?

If you experience any of these symptoms, start by voicing your concerns and symptoms to your primary care provider. From there, your doctor may suggest seeing an oncologist for more specialized treatment. 

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