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Wilms' Tumor

Childhood kidney cancer


Updated June 02, 2005

Wilms' tumor (cancer of the kidney) is a sneaky kind of cancer. Most of these tumors are found only after they have become large enough to cause a problem. A typical first sign that there might be a problem is that a child's diaper or pants no longer fit at the waist, and that the child's belly seems swollen. Sometimes the tumor makes the child feel ill or vomit.

Who gets it?
Wilms' tumor most often occurs in otherwise healthy children between 3 and 4 years old. It seems to occur more often among African Americans and among girls. It can occur in adolescents or adults, but this is very rare. Only 1-2% of cases have any family history of Wilms' tumor. The tumor seems to result from changes in one or more specific genes.

The typical weight of the tumor at discovery is ½ pound. It is not difficult for a physician to feel a tumor the size of a baseball on the child's kidney, but usually the child has an ultrasound or CT scan to confirm the diagnosis. Most of the time a tumor develops on only one kidney, but in 5-7% of cases there is cancer in both kidneys.

There is a system, called staging, that classifies Wilms' tumors into groups according to characteristics of the cancer. Treatment depends on what stage the tumor is at when it is discovered, and the age of the child. Most of the time Wilms' tumor is found before it has spread (metastasized) to other parts of the body, so removing the tumor usually works well. Some children receive chemotherapy or radiation before and/or after surgery to reduce the size of the tumor and kill off more cancer cells.

More than 90% of children with Wilms' tumor are surviving five years after diagnosis, meaning that this cancer is one of the most curable.

Clinical trials
At present, there are a number of studies being conducted to improve the treatment of Wilms' tumor. Researchers are looking at what are the best combinations of chemotherapy and radiation to use, as well as stem cell transplantation, for hard-to-cure tumors, or ones that grow back after treatment. For more information about these studies and participation, see the Clinicaltrials.gov site.

Information for this article was taken from:
American Cancer Institute. Cancer Reference Information: Wilms' Tumor.
National Cancer Institute. CancerNet PDQ for Health Professionals. Available online.

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