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Wilms tumor

Alternative Name

Nephroblastoma; Kidney Tumor


Wilms tumor is a rare tumor that can occur in one or both kidneys with 500 new cases diagnosed each year in the United States. Though Wilms tumor can occur in older children most patient's are diagnosed between 2-3 years of age.

Also known as nephroblastoma, the tumor is believed to begin growing as a fetus develops in the womb. Some of the primitive cells that are destined to form into the kidneys mistakenly continue to grow out of control and form a tumor. Fortunately, Wilms Tumor is highly treatable and most kids go on to live normal lives.

Review Date: 7/13/2011

Reviewed By: Chatchawin Assanasen, MD Assistant Professor Pediatric Hematology-Oncology, CTRC


Most children do not show any signs of having cancer prior to diagnosis. Often, a parent or family member may discover a firm, smooth lump in the child's abdomen. It is not uncommon for the mass to grow quite large before it is discovered ― the average Wilms tumor is 1 pound at diagnosis.

Some children do have abdominal pain other symptoms such as nausea, high blood pressure (hypertension), blood in the urine, loss of appetite, constipation, or fever.

Even though Wilms tumors often are large when found, most have not spread (metastasized) to other areas of the body.


An ultrasound scan is usually the first investigation to confirm the presence of an abdominal mass.  This test uses sound waves rather than radiation to create an image for the doctors to view.

Computed Tomography (CT or CAT) scans of the abdomen and chest are the most accurate investigation to determine any evidence of both local and distant tumor spread.

Magnetic resonance imaging (MRI) uses electromagnetic waves and strong magnets to produce detailed pictures of the internal parts of the body.

Laboratory tests such as blood and urine tests check the general health of a patient.

Rarely Wilms tumors can be hereditary ("running in the family").  Gene mutations named WT1, WT2, and WTX have been highly associated with certain types of Wilms tumors.  Currently, there is no commercially available test to screen those who may pass the disease onto their offspring.  Certain genetic factors like birth defect syndromes can also increase the likelihood of developing the disease. These include:

  • Beckwith-Wiedemann syndrome (a condition associated with abnormal enlargement internal organs)
  • WAGR (marked by absence of the iris and defects in the kidneys, urinary tract, or genitalia)
  • Denys-Drash syndrome (defect external genitals in boys)

Cancer genetics counseling services are conducted at both the Cancer therapy and Research Center (CTRC) and CHRISTUS Santa Rosa Children's Hospital providing comprehensive, and compassionate state-of-the art clinical care to patients and families at high risk for cancer and expert clinical evaluations to patients referred to the UT Medicine/School of Medicine and its affiliated health programs.


Treatment for Wilms tumor is determined by many factors, the most important being the stage of the cancer at diagnosis, and the microscopic details (histology) of the cancer cells. "Favorable" histology is associated with a good chance of a cure; tumors with "unfavorable" histology are more aggressive and difficult to cure.

Early treatment for Wilms tumor primarily involved surgery.  But there was some evidence that chemotherapy and or radiation may also be beneficial.  Organized clinical investigation was limited until the establishment of the National Wilms Tumor Study (NWTS) in 1969. This provided a cooperative group effort among several institutions to treat patients in a clearly defined manner so that understanding of the disease and treatments could be advanced.  The faculty and staff at UT Medicine / CTRC are pleased to have been a part of this pioneering cooperative effort.  Click here to meet the Pediatric Oncology Team.

Most treatment plans for Wilms tumor usually include both surgery and chemotherapy.  The more advanced stages also may require radiation therapy. Chemotherapy uses drugs (administered either orally or intravenously) to enter the bloodstream, circulate throughout the body, and kill cancerous cells wherever they may be. Radiation uses high-energy X-ray beams to kill specific cells in different areas of the body. Click here to learn more on Radiation Oncology.

Both treatments have short-term and long-term risks. Temporary or short-term discomfort may include nausea and vomiting, loss of appetite, mouth sores, fatigue, loss of hair, weakened immune system (leaving a patient vulnerable to infection), and bleeding or bruising.

Long-term effects may include the development of secondary cancers (like leukemia) or the weakening of some internal organs, such as the heart.  All pediatric oncology patients continue to be evaluated in our Long Term Follow-up Clinic to identify and intervene early on should anything arise.  However, these risks are minimal ― the benefits of treatment far outweigh potential risks.

Pediatric Hematology / Oncology

If you would like to request an appointment with a physician, or if there is a direct referral from a physician, please call:

Appointments: (210) 704-2187

Fax: (210) 704-2396