What is Wilms' tumor?

Wilms' tumor is a cancer of the kidney. It is also known as nephroblastoma. It most often affects children between 3 and 8 years of age. Wilms' tumor usually only affects one kidney, but it may affect both kidneys.

The kidneys are located on each side of the spine just above the waist. They make urine by filtering waste products from the blood. They control the balance of salt and water in the body and help regulate blood pressure.

What is the cause?

The exact cause of this tumor is unknown. The tumor is linked with certain birth defects, such as problems with the genital or urinary tract, absence of the iris of the eye (aniridia), and hemihypertrophy (enlargement of one side of the body). It tends to run in families, and may caused by changes in certain genes.

What are the symptoms?

Your child may appear healthy or may have:

• a lump that can be felt in the abdomen
• blood in the urine
• constipation
• fever
• nausea or vomiting
• night sweats
• loss of appetite
• stomach pain
• weight loss.

Wilms' tumors can grow quite large without causing pain.

How is it diagnosed?

Wilm's tumor may be hard to diagnose. Sometimes tumors are found when x-rays are taken for other reasons. Your child's health care provider will ask about symptoms and examine your child. The provider will want to know if there's a family history of cancer or birth defects of the genitals or urinary system.

Tests may include:

• blood tests
• urine tests
• intravenous pyelogram (a kidney x-ray also called an IVP)
• ultrasound of the kidneys
• CT scan or MRI
• arteriogram (a special x-ray of the arteries and veins of the kidney).

Your child may also have a chest X-ray or bone scan to find out if the cancer has spread beyond the kidneys.

How is it treated?

Therapies for your child may include:

• Surgery. Surgery may be needed to remove the tumor. Surgery to remove kidney tissue is called nephrectomy.
• Chemotherapy. Chemotherapy uses powerful drugs to kill cancer. The medicine may be taken by mouth or injected into the spinal fluid, a vein (intravenous), or muscle. Unfortunately, chemotherapy has some side effects including hair loss, vomiting, anemia, nausea, and fatigue. At high doses chemotherapy can destroy bone marrow. Your child's provider may suggest that marrow be removed before treatment and frozen. After chemotherapy, the marrow will be reinfused. This is called autologous bone marrow reinfusion.
• Radiation therapy. Radiation uses high-energy waves or particles to kill cancer cells or shrink the tumor. Possible side effects include skin irritation, nausea, diarrhea, and tiredness. After treatment, you need to use a sun-blocking lotion on your child's skin to avoid sunburn. With treatment, Wilms' tumor can usually be cured.

Where can I get more information?

Candlelighter's Childhood Cancer Foundation is a national support organization. It provides support for children with cancer and their parents. There are support groups for parents, funding for transportation, and sending child cancer patients to special summer camps. Call 800-366-2223 or visit their Web site at http://www.candlelighters.org. Other resources include the American Cancer Society at 800-ACS-2345 or http://www.cancer.org ; and the National Cancer Institute at 800-4-CANCER or http://www.cancer.gov.