Risk factors

Factors that may increase the risk of Wilms' tumor include:

• African-American race. In the United States, African-American children have a slightly higher risk of developing Wilms' tumor than children of other races. Asian-American children appear to have a lower risk than children of other races.
• Family history of Wilms' tumor. If someone in your child's family has had Wilms' tumor, then your child has an increased risk of developing the disease.

Wilms' tumor occurs more frequently in children with certain abnormalities or syndromes present at birth, including:

• Aniridia. In aniridia (an-ih-RID-e-uh), the iris — the colored portion of the eye — forms only partially or not at all.
• Hemihypertrophy. Hemihypertrophy (hem-e-hi-PUR-truh-fee) means one side of the body or a part of the body is noticeably larger than the other side.

Wilms' tumor can occur as part of rare syndromes, including:

• WAGR syndrome. This syndrome includes Wilms' tumor, aniridia, genital and urinary system abnormalities, and intellectual disabilities.
• Denys-Drash syndrome. This syndrome includes Wilms' tumor, kidney disease and male pseudohermaphroditism (soo-do-her-MAF-roe-dit-iz-um), in which a boy is born with testicles but may exhibit female characteristics.
• Beckwith-Wiedemann syndrome. Children with this syndrome tend to be significantly larger than average (macrosomia). Other signs may include abdominal organs that jut out into the base of the umbilical cord, a large tongue (macroglossia), enlarged internal organs and ear abnormalities. There is also an increased risk of tumors, including a type of liver cancer called hepatoblastoma.