Wilms tumor is a cancer that grows in the kidneys. These tumors usually develop during childhood. All Wilms tumors are cancerous (malignant).
The cause of Wilms tumor is not always known, but some children may have a genetic abnormality that increases their risk of developing it.
Children usually have a lump in their abdomen, and they may also have abdominal pain, fever, poor appetite, nausea, and vomiting.
An imaging test is done to determine the consistency and size of the lump.
Treatment involves surgery and chemotherapy and sometimes radiation therapy.
(See also Overview of Childhood Cancer.)
Wilms tumor usually develops in children younger than 5 years old, but it occasionally occurs in older children. It is very rare in adults. Wilms tumor typically grows in only one kidney, but in about 5 to 10% of people it grows simultaneously in both kidneys.
For most people, the cause of Wilms tumor is not known. For others, the cause is a lack of certain genes or another genetic abnormality. Most people with Wilms tumor do not have a family member who has this cancer.
Wilms tumor may develop in some children who have certain birth defects, especially of the kidneys, genitals, and urinary tract, and in children who have one side of the body that grows larger than the other side. These defects, as well as intellectual disability, may be caused by a genetic abnormality.
Symptoms of Wilms Tumor
The most common symptom of Wilms tumor is a painless lump in the abdomen. The abdomen may enlarge, which parents may notice when children suddenly need a larger diaper size.
Less often, children may have abdominal pain, fever, poor appetite, nausea, and vomiting. Blood appears in the urine of some children.
Because the kidneys are involved in controlling blood pressure, Wilms tumor may cause high blood pressure (hypertension).
This cancer can spread to other parts of the body, especially the lungs, but is usually found before causing shortness of breath, cough, or other symptoms.
Diagnosis of Wilms Tumor
A doctor's examination
Ultrasonography, computed tomography (CT), or magnetic resonance imaging (MRI) of the abdomen
Blood tests
Often surgery to remove the tumor at the time of diagnosis
Wilms tumor is most often detected when parents notice a lump in the child’s abdomen and take their child to a doctor. Or a doctor may feel such a lump during a routine examination.
If the doctor suspects Wilms tumor, several imaging tests are done. Ultrasound of the abdomen is done to determine the consistency and size of the lump. A CT scan or MRI scan of the abdomen is done to help doctors determine whether the tumor has spread to nearby lymph nodes, the liver, or to the other kidney. Doctors sometimes do other imaging tests such as bone scans and a special type of positron emission tomography (PET) scan to determine how far the cancer has spread.
The doctor also does CT scan of the chest to determine whether tumors have spread to the lungs.
Doctors do blood and sometimes urine tests to evaluate organ function and detect abnormalities.
Surgery to remove part or all of the kidney (nephrectomy) that contains the tumor is done in most children based on the results of the imaging tests. Doctors then analyze the tumor to confirm it is a Wilms tumor and do additional genetic tests on it.
During surgery, doctors also remove nearby lymph nodes and analyze them for cancer cells. Cancer that has spread to the lymph nodes may require different treatment than cancer that has not.
Treatment of Wilms Tumor
Surgery and chemotherapy
Sometimes radiation therapy
(See also Cancer Treatment Principles and Surgery for Cancer.)
Treatment options for Wilms tumor depend on where the child is going to receive treatment. In North America, doctors first remove the kidney that contains the tumor and then give the child chemotherapy. In Europe, doctors first give the child chemotherapy and then remove the tumor. In both locations, most children are given chemotherapy (most commonly dactinomycin and vincristine and sometimes doxorubicin) after surgery, and some children are also given radiation therapy.
Rarely, some children under 2 years of age who have small tumors can be cured by surgery alone.
Rarely, the tumor is extremely large and cannot be removed initially, or tumors are in both kidneys. In such cases, children are first treated with chemotherapy to shrink the tumor or tumors. Then the tumor or tumors are removed.
If the cancer has spread to the lungs, children are sometimes also treated with radiation therapy.
Prognosis for Wilms Tumor
In general, Wilms tumor is very curable.
If the tumor is in only 1 kidney, most children are cured. Even if the tumor has spread beyond the kidney or the child's cancer is advanced, many children do well with treatment.
The outcome is usually better in children who:
Are younger
Have cancer cells that are less abnormal when the tumor is examined under a microscope
Have a tumor that has not spread and can be fully removed during surgery
Do not have certain gene abnormalities
Wilms tumor can return, typically within 2 years of diagnosis. Children whose cancer has returned can still be cured.
More Information
The following English-language resource may be useful. Please note that The Manual is not responsible for the content of this resource.
American Cancer Society: How to Cope if Your Child Has Cancer
Drug Information for the Topic
