Wilms tumors are cancerous tumors that form in the kidneys. They are the most common type of kidney cancer in children and rarely form in children older than age six.

Wilms tumors can spread to the lungs, liver, or lymph nodes. The outlook for patients depends on whether the tumor or tumors can be completely removed, the age of the child, and the stage of the tumor.

Symptoms of Wilms Tumors

Symptoms vary depending on the type of cancer. Many of the symptoms of childhood cancers can also be symptoms of other diseases. Be sure to consult your doctor if your child has symptoms that seem unusual for him or her.

Below are symptoms that often occur with Wilms tumors:

• A lump or swelling in the abdomen
• Pain in the abdomen
• Lack of appetite
• Nausea or vomiting
• Blood in the urine
• Unexplained fever

Stages

In addition to being divided into four stages, Wilms tumors are classified according to how they appear under the microscope (their histology).

Tumors with a favorable histology respond better to chemotherapy and have a better outlook than those classified as anaplastic, which have cells that are of abnormal shape and size. Most Wilms tumors are classified as favorable.

The four stages of Wilms tumors are:

• Stage I: The tumor is confined to the kidney and can usually be removed with surgery.
• Stage II: The tumor has spread to nearby tissues, such as fat or blood vessels, but it can still be entirely removed by surgery.
• Stage III: The cancer has spread to other structures in the abdomen, such as lymph nodes or other tissues. It may not be fully removed by surgery.
• Stage IV: The tumor has spread to distant parts of the body, such as the liver, the lungs, or the brain.

There is also a special designation for Wilms tumor that affects both kidneys:

• Stage V: There is cancer in both kidneys.

Treatment Options

Surgery, chemotherapy, and radiation therapy are the standard treatments for many childhood cancers. Your child may receive one or more treatments depending on the stage or grade of the cancer, your child’s general health, and other factors.

Surgery is the main treatment for Wilms tumor. In most cases, the tumor is in only one kidney, so the kidney may be removed. If there are tumors in both kidneys, only a portion of the kidney or kidneys may be removed.

If both kidneys must be removed, the child will need to have dialysis (a procedure in which a machine removes waste products from the blood) until a kidney transplant can be performed.

Chemotherapy, radiation, or both may also be used after surgery to kill any remaining cancer cells. Children with larger stage tumors may undergo chemotherapy before surgery to shrink the tumor.

Learn more about pediatric cancer:

• Chemotherapy for Pediatric Cancer
• Radiation Therapy for Pediatric Cancer
• Pediatric Cancer Risk Factors
• Late Effects of Pediatric Cancer Treatment