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Wilms' Tumor: A Childhood Kidney Cancer

Also called nephroblastoma, Wilms' tumor is a rare type of kidney cancer that causes a tumor to develop on either one or both kidneys. The condition is named after Carl Max Wilhelm Wilms, a German doctor who, in 1899, was one of the first to study the disease.

Wilms' Tumor and Children

Unfortunately, Wilms' tumor affects children, mostly those between the ages of three and eight. In fact, it's the most common kidney cancer in children.

Some birth defects and certain genetic conditions can increase the likelihood that a child will develop this childhood cancer. These include:

aniridia: a condition that causes the iris to form improperly
cryptorchidism: when one or both of the testicles fail to descend
hemihypertrophy: when one side of the body is larger than the other.

It's also more common if a relative has had Wilms' tumor.

If a child is born with a birth defect or has a genetic predisposition for childhood Wilms' tumor, then they should have a specialist perform both a physical exam and an ultrasound every three months to screen for tumors.

Only about five percent of children develop tumors on both kidneys (bilateral). The majority of children have tumors affecting only one kidney (unilateral).

Kidney Tumor Symptoms

Unfortunately, Wilms' tumors often go unnoticed in the early stages. The tumors are usually discovered only after they've grown to a fairly large size or after they've spread to other organs (metastasized).

Possible symptoms include:

blood in the urine
constipation
fever
high blood pressure
lump or swelling in the abdomen (the most common symptom)
nausea
reduced appetite
stomach pain
vomiting.

If you feel a lump or swelling in your child's abdomen or if your child experiences any of the above-mentioned symptoms, immediately schedule an appointment with a pediatrician.

Wilms' Tumor Diagnosis

An initial Wilms' tumor diagnosis can be made with the help of an ultrasound, MRI or CAT scan. If a diagnosis is made, the doctor will then have to determine the stage of the cancer.

He will also have to determine whether the cancer has a favorable or unfavorable appearance. Ninety-five percent have a favorable appearance and a good prognosis. In roughly 5 percent of the cases, however, the nuclei of the cells have grown large and distorted, and the cells' appearances vary widely (anaplasia). This diminishes the prognosis.

This type of kidney cancer can be divided into five stages:

Stage I: The tumor is only in the kidney and can be completely removed by surgery. This stage accounts for 42 percent of cases.
Stage II: The cancer has grown beyond the kidney but can still be removed surgically. This stage accounts for 22 percent of cases.
Stage III: In this stage, the cancer has spread to the lymph nodes in the abdomen or pelvis or to nearby vital structures or tumor implants have reached the lining of the abdominal cavity. This type cannot be completely removed by surgery. This accounts for 22 percent of cases.
Stage IV: The cancer has spread through the bloodstream to other organs such as the liver, lungs, bone, brain or distant lymph nodes. This stage accounts for nine percent of cases.
Stage V: Tumors have occurred in both kidneys at the time of diagnosis. This accounts for five percent of cases.

Wilms' Tumor Cancer Treatments

More than 92 percent of children with this childhood cancer are completely cured, and new methods of treatment are constantly in development.

Treatment usually occurs in children's cancer centers, since doctors at those facilities have the most experience with this rare disease.

Treatments can include:

biologic therapy
chemotherapy
radiation therapy
surgery to remove the tumor.

Treatments can also include a combination of the above treatment options.

Prognosis for Wilms' Tumor

The good news is that childhood Wilms' tumor has an excellent prognosis. In fact, most children with Wilms' tumor will survive the disease.

Divided into stages, the prognosis is as follows:

Stage I: 96 percent four-year survival rate for favorable tumors, 93 percent for unfavorable tumors
Stage II: 91 percent survival rate for favorable tumors, 70 percent for unfavorable tumors
Stage III: 91 percent for favorable tumors, 56 percent for unfavorable tumors
Stage IV: 81 percent survival rate for favorable tumors, 17 percent for unfavorable tumors
Stage V: 82 percent for favorable tumors, unknown for unfavorable tumors.

Resources

American Cancer Society (2006). Detailed Guide: Wilms' Tumor. Retrieved July 10, 2007, from the American Cancer Society Web site: http://www.cancer.org/docroot/CRI/content/
CRI_2_4_1x_What_is_wilms_tumor_46.asp?sitearea=

Mayo Clinic (2005). Wilms' Tumor. Retrieved July 10, 2007, from the Mayo Clinic Web site: http://www.mayoclinic.com/health/wilms-tumor/DS00436

National Cancer Institute (n.d.). Wilms' Tumor. Retrieved July 10, 2007, from the National Cancer Institute Web site: http://www.nlm.nih.gov/medlineplus/wilmstumor.html

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