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A risk factor is anything that affects the chance of having a
disease such as cancer. Different cancers have different risk factors.
For example, exposing skin to strong sunlight is a risk factor for skin
cancer.
But risk factors don't tell us everything. Having a risk
factor, or even several, does not mean that a person will get the
disease, and many people get cancer without having any known risk
factors.
Although lifestyle-related risks (such as smoking and obesity)
are significant factors in many cancers of adults, they tend to have
little or no effect on childhood cancer risk. For most Wilms tumors
these is no clear cause.
Environmental risk factors
So far research has not found any strong links between Wilms
tumor and environmental factors, either before or after a child's
birth.
Genetic and hereditary risk factors
Family history of Wilms tumor
Between 1% and 3% of children with Wilms tumors have one or
more relatives with the same cancer. Scientists think that these
children inherit chromosomes with an abnormal or missing gene from a
parent that increases their risk of developing Wilms tumor.
Children with these familial cases of Wilms tumors are
slightly more likely than children with sporadic cases (no relatives
with Wilms tumor) to have tumors in both kidneys. But most familial
cases affect only 1 kidney.
Certain inherited syndromes/birth defects
There is a strong link between Wilms tumors and certain kinds
of birth defects. About 1 out of 10 children with Wilms tumor also have
birth defects. Most birth defects linked to Wilms tumors occur in
syndromes. Syndromes are groups of symptoms, signs, malformations, or
other abnormalities that occur together in the same person. Those
linked to Wilms tumor include:
WAGR syndrome: Children
with this syndrome have about a 50% chance of having a Wilms tumor. It
is caused by the loss (deletion) of part of chromosome 11, where the
WT1 gene is normally found. WAGR stands for:
- Wilms
tumor
- Aniridia
(complete or partial lack of the iris [colored area] of the eyes)
- Genitourinary
tract abnormalities (defects of the kidneys, urinary tract, penis,
scrotum, clitoris, testicles, or ovaries)
- mental Retardation
Beckwith-Wiedemann
syndrome: Children with this syndrome tend to be big for
their age. They also have larger than normal internal organs and often
have an enlarged tongue. They may have an oversized arm and/or leg on
one side of the body (hemihypertrophy), as well as other medical
problems. They have about a 5% to 10% risk of having Wilms tumors.
Denys-Drash
syndrome: This rare syndrome has been linked to changes
(mutations) in the WT1 gene. In this syndrome the kidneys become
diseased and stop working when the child is very young. Wilms tumors
usually develop in the diseased kidneys. The reproductive organs do not
develop normally. In boys, the penis, testicles, and scrotum do not
develop, which may cause them to be mistaken for girls. Because the
risk of Wilms tumors is very high, most doctors advise removing the
kidneys soon after this syndrome is diagnosed.
Other syndromes
or birth defects: Less often, Wilms tumor has been linked
to other syndromes, including:
- Perlman syndrome
- Sotos syndrome
- Simpson-Golabi-Behmel syndrome
- Bloom syndrome
Wilms tumor is also more common in children with certain birth
defects:
- aniridia (complete or partial lack of the iris [colored
area] of the eyes)
- hemihypertrophy (an oversized arm and/or leg on one side of
the body)
- cryptorchidism (failure of the testicles to descend into
the scrotum) in boys
- hypospadias (defect in boys where the urinary opening is on
the underside of the penis)
Other risk factors
Race
In the United States, the risk of having Wilms tumor is
slightly higher in African-American children than in white children and
is lowest among Asian-American children. The reason for this is not
known.
Sex
The risk of having Wilms tumors is slightly higher in girls
than in boys.
Last Medical Review: 09/14/2009
Last Revised: 09/14/2009
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