About Wilms Tumor
Wilms tumor is the most common form of kidney cancer in children. About 500 children are diagnosed with in the United States each year and about 75% of those patients are under 5 years old. Other common kidney cancers include renal cell carcinoma (in children age 15-19), clear cell carcinoma (in children under age 4) and rhabdoid tumor (in infants).
Typically, cases of Wilms tumor are not diagnosed until the tumor becomes quite large. Fortunately, most tumors are discovered before they metastasize (spread to other organs in the body). As with many cancers, the tumor mass can become quite large; the average weight of a newly discovered tumor is about 500 grams (one pound), which is larger than the normal kidney.