Wilms’ Tumor

What is Wilms' tumor?

Wilms' tumor is a cancer found in one or both kidneys and usually occurs in children between the age of two and six years. It is a rare disease, found in about 400 children in the U.S. each year. The cause of this tumor is not known. It is not contagious, and nothing you have done or not done is responsible for your child's tumor.

What are the symptoms of Wilms' tumor?

Wilms' tumors are usually large lesions that grow rapidly. The most common presenting sign of Wilms' tumor is an abdominal mass in an apparently healthy child. Parents often notice a swollen abdomen. Many times, the parents are the first to feel a lump in the belly during bathing or dressing. The child may have high blood pressure (hypertension), blood in the urine (hematuria), or abdominal pain.

How is Wilms' tumor diagnosed?

Since Wilms' tumor may spread, usually to the lungs or liver, your child will undergo various tests to assess the extent of disease. A careful diagnosis is very important to determine the most effective treatment. Any or all of the following tests may be done:

  • Ultrasound. This test uses sound waves to outline your child's kidneys.
  • X-rays. X-rays of the abdomen and chest are done to look for spread of the disease.
  • Computed tomography (CT scan). This test produces images of the scanned body parts. The abdomen and chest usually are scanned. Frequently, dye is injected into a vein to help the radiologist outline the tumor areas.
  • Blood tests. A complete blood count and/or blood chemistries test may be ordered.
  • HVA/VMA urine collection. This urine test helps to rule out another kind of abdominal tumor.
  • Urinalysis. An analysis of the urine may be ordered.
  • Renal function test. This test uses blood or urine samples to measures the functioning of the kidneys.

After the required tests are finished your child will have exploratory surgery. This type of surgery is called an exploratory laparotomy. Under general anesthesia the surgeon makes an incision in your child's abdomen in order to look at the abdominal organs.

The surgeon often will remove the kidney with the tumor. This is called a radical nephrectomy. The surgeon also will take samples of the tissue surrounding the kidney. This tissue may include nearby lymph nodes and, possibly, tissue from the other kidney. These specimens are examined by a pathologist. A pathologist is a doctor who tests tissue for disease using a microscope and other biology tests. Examining cells under the microscope will confirm the Wilms' tumor diagnosis and also will help show if the tumor has spread outside of the kidney. Often, the slides of tumor tissue will be sent to a central reference laboratory for further confirmation. A central reference lab has equipment and personnel specialized in diagnosis of cancer and other illnesses. A specimen collected at the time of diagnosis can be sent to a central reference lab and compared to a known specimen to verify diagnosis of a suspected condition.

Once the tests are complete, a group of doctors (oncologists, radiologists, pathologists and surgeons) discuss your child's condition and decide on the most effective treatment plan. They consider your child's age, general condition and the stage of the disease. Staging is a method of determining how far the disease has spread. The staging system used is as follows:

  • Stage I. The tumor is completely removed during surgery and was only in the kidney.
  • Stage II. The tumor has spread beyond the kidney, to fat or soft tissue or blood vessels. The tumor can be completely removed during surgery.
  • Stage III. The tumor has spread within the abdomen and cannot be entirely removed by surgery. The tumor may have spread to the lymph nodes or tissue near the kidney but does not extend beyond the structures of the abdomen.
  • Stage IV. The tumor has spread beyond the abdomen, possibly to the liver, lungs, bone, and/or lymph nodes outside the abdomen.
  • Stage V. Tumors are in both kidneys when the disease is first diagnosed. The disease may or may not have spread to other parts of the body.

Examination of the tumor cells under the microscope also determines the histology, or microscopic characteristics, of the tumor. The histology shows if the tumor cells have characteristics that are associated with recurrence. Both the histology and the stage determine your child's treatment.

How is Wilms' tumor treated?

The treatment plan includes the surgery mentioned above, chemotherapy, and possibly radiation therapy and is explained to you in detail. Most of your child's treatment will be done as an outpatient in the cancer and blood disorders clinic.

Radiation therapy is used to destroy tumor cells that may have escaped from the tumor. Chemotherapy is used to destroy any metastatic tumor cells in the bloodstream.

Throughout the course of therapy and after treatment is completed, various follow-up studies such as blood tests, x-rays and CT scans will be done to closely monitor your child. Because of research completed on Wilms' tumor, excellent progress has been made in treating it successfully. Current research is focusing on refining treatment. It may be possible to minimize treatment for children with a good prognosis. Children with metastatic disease or unfavorable histology may benefit from more intense treatment.

About treatment for Wilms' tumor at Children's

Children's cancer and blood disorders program consistently achieves treatment results ranking it as one of the top 10 programs in the U.S. Children's treats the majority of children with cancer and blood disorders in Minnesota and provides patients with access to a variety of clinical trials of groundbreaking new treatments. Through our renowned solid tumors program, patients experience unparalleled family support, a nationally renowned pain management team, and compassionate, coordinated care.

Contact Us

If you are a family member looking for a Children's hematologist or oncologist or wanting to schedule an appointment, please call our clinic at Children's – Minneapolis at (612) 813-5940.

If you are a health professional looking for consultation or referral information, please call Children's Physician Access at 1-866-755-2121 (toll-free) and ask for the on-call hematologist/oncologist.