About this Cancer

Wilms' tumor is a type of kidney cancer most commonly affecting children under age five. The kidneys are a pair of organs, found at the back of the abdomen, that filter the blood to remove excess fluids and waste products, which are then converted into urine. Wilms’ tumor occurs in approximately one of our every 200,000 children.

Wilms’ tumor arises from very specialized cells known as nephroblasts, which are involved in the development of the kidneys during fetal development in the womb. These cells usually disappear at birth. In children with Wilms' tumor, however, they can still be found.

Wilms’ tumor is named after Dr. Max Wilms who first described it.  Nephroblastoma is another name for the disease.

Risk Factors

In most children the cause is unknown. In some rare instances, children who have Wilms' tumor also have a non-inherited condition present at birth (congenital malformations), such as lack of an iris in the eye (aniridia); abnormalities of the genitals; and/or a condition in which one side of the body is slightly larger than the other (hemihypertrophy).

Cancer Symptoms

The most common symptom is a swelling in the abdomen, which is usually painless. Occasionally, the tumor may bleed slightly and this can cause irritation in the area, which may be painful. There may be blood in the child's urine or the blood pressure may be raised. The child may also have a high temperature (fever), upset stomach, weight loss, or lack of appetite.

Diagnostic Tests

A biopsy, in which a portion of the tumor is surgically removed and studied by a pathologist under a microscope for the presence of cancer cells, will confirm a diagnosis of Wilms’ tumor.  Blood tests, urine tests, chest X-rays, ultrasound or CT (computerized tomography) scans may be ordered to check for any spread of the disease.

Treatment

All children with Wilms' tumor will have surgery. Initially, this may only be a biopsy to confirm the diagnosis. Chemotherapy (treatment with anticancer drugs) is then given to shrink the tumor before the kidney is removed.  The removal of the kidney is known as a nephrectomy. Usually, a nephrectomy is performed first, and chemotherapy is given afterwards.

Depending on the stage of the disease at diagnosis, radiation therapy (treatment with targeted X-rays that destroy cancer cells) may be given to the side of the abdomen where the tumor was found.

When one kidney is removed the other will be able to work as normal and work for both kidneys. Children with Wilms’ tumor are closely followed to check for any recurrence. Most children with Wilms' tumor are cured, but if the cancer comes back it is usually within the first two years.