Wilms tumor is a solid cancerous tumor of the kidney that arises from immature kidney cells.
For most children with Wilms tumor, no clear cause is known. Certain environmental factors (such as contact with toxic chemicals) may increase the risk of developing this disease, but more research is needed.
Children are more likely to develop Wilms tumor if they also have the following:
- WAGR syndrome (Wilms tumor-aniridia-genitourinary malformation-retardation)
- Denys-Drash syndrome
- Beckwith-Wiedemann syndrome
About 1.5% of children with Wilms tumor have a family member with the disease (familial Wilms tumor). About 5 to 10% of children with Wilms tumor have tumors in both kidneys (called bilateral tumors), which may be inherited.
- Sometimes more than one Wilms tumor is present in the affected kidney. This does not mean the disease has spread.
- Each of the tumors develops on its own and may come from immature cells called “nephrogenic rests” within the kidney.
- If Wilms tumor spreads, it will be partly because of genetics and partly because of how far the disease has progressed.
- Wilms tumor may spread into the blood vessels surrounding the kidney as a tumor clot (thrombus). The other common site for spread is the lungs.
How common is Wilms tumor?
- Wilms tumor is the fourth most common type of childhood cancer and the most common type of kidney cancer in children.
- , affecting about one in every 10,000 children. As many as 5% of cancers diagnosed each year are Wilms tumor.
- Children with Wilms tumor in one kidney are usually diagnosed around 3 years of age. Children with Wilms tumor in both kidneys are usually diagnosed around 2 years of age.
- Males and females are equally affected.
What are the symptoms of Wilms tumor?
Wilms tumors can grow quite large before any symptoms develop. When they do appear, symptoms may be similar to those of other diseases.
One of the earliest symptoms that may be noticed is a large lump or hard mass in your child’s belly (abdomen). Their belly may also appear much larger than usual. This is most often found when dressing, bathing, or changing your child’s diaper.
Other symptoms of Wilms tumor include:
- Fever
- Nausea
- Loss of appetite
- Blood in the urine
- Constipation
- High blood pressure (hypertension)
- Shortness of breath
- A fever that won’t go away
How is Wilms tumor treated?
Treatment involves a combination of surgery and chemotherapy and may also involve radiation therapy (for patients with advanced disease).
In the United States, the tumor is almost always removed as soon as it is found. In Europe, the patient usually receives several weeks of chemotherapy first. Both methods produce high rates of treatment success.
- Surgery — is used to remove the tumor(s). For patients with unilateral Wilms tumor, the entire kidney is often removed with the tumor.
- Difficult-to-remove tumors and bilateral tumors are usually treated first with chemotherapy to shrink them and make them easier to remove.
- Chemotherapy (“chemo”) — uses powerful medicines to kill cancer cells or stop them from growing (dividing) and making more cancer cells:
- Chemo is injected into the bloodstream through a large central catheter (“central line”), so that it can travel throughout the body.
- Combination therapy uses more than one type of chemo at a time and is needed to treat Wilms tumor.
- Chemo is given to either shrink tumors before surgery, to protect the patient from having any tumor cells spread to other parts of the body, or to treat disease that has already spread outside the primary tumor.
If the tumor has spread outside the kidney into the abdomen or lungs, the child will require more intensive chemo and will receive radiation directed specifically at the tumor site(s).
For Wilms tumor that has returned (recurred), treatment depends on how far the disease has spread and which treatments were already used.
What are the survival rates for Wilms tumor?
Long-term survival rates are excellent:
- About 85 to 90% of Wilms tumor patients with favorable histology can be cured. Histology is the way cells look under the microscope—in this case tumor cells.
- Cure rates for patients with anaplastic histology, a more aggressive form of Wilms tumor, are lower.
- Patients who are treated for Wilms tumor should continue close medical follow-up, since chronic health problems occur in 25% of survivors. These health problems are related to high blood pressure and heart and kidney function.
