WILMS TUMOR
Category: Child Health
Abstract : What is Wilms tumor? Wilms tumor, also called nephroblastoma, is a malignant
(cancerous) tumor originating in the cells of the kidney. It is the most common
type of renal (kidney) cancer and accounts for about 6 percent of all childhood
cancers. Approximately 400 to 500 children in the US are diagnosed with a Wilms
tumor each year. The disease can occur at any age between infancy a
What is Wilms tumor?
Wilms tumor, also called nephroblastoma, is a malignant
(cancerous) tumor originating in the cells of the kidney. It is the most common
type of renal (kidney) cancer and accounts for about 6 percent of all childhood
cancers. Approximately 400 to 500 children in the US are diagnosed with a Wilms
tumor each year.
The disease can occur at any age between infancy and 15
years, but, in most cases, the tumor is detected by the age of 3. This cancer
affects males and females equally.
The tumor can be very large and it may
spread (metastasize) to other body tissues. The most common site for Wilms tumor
to metastasize is the lungs. Lesions may also occur, however, in the liver, the
other kidney, brain, and/or bones. In approximately 5 to 10 percent of children
with Wilms tumor, both kidneys are involved.
What causes Wilms
tumor?
It is uncommon for Wilms tumor to run in families. Less than 2 percent
of cases will have an affected relative. Most cases of Wilms are considered
sporadic (occur by chance) and are the result of genetic mutations that affect
cell growth in the kidney. These mutations generally arise after birth, but, in
some cases, children are born with a genetic alteration that predisposes them to
cancer.
A small percentage of patients with Wilms tumor have one of three
genetic syndromes, including the following:
- WAGR syndrome - the acronym WAGR stands for the four diseases present
in WAGR syndrome, including: Wilms tumor, aniridia (absence of the iris, the
colored part of the eye), genitourinary malformations, and mental retardation.
This is caused by loss or inactivation of a tumor suppressor gene called WT1 on
chromosome #11. Tumor suppressor genes usually suppress the growth of tumors and
control cell growth. When altered, they no longer control cell growth, and
tumors may form.
- Denys-Drash syndrome - this syndrome is characterized by kidney
failure, genitourinary malformations, and tumors of the gonads (ovaries or
testes). This is also caused by loss or inactivation of a tumor suppressor gene
called WT1 on chromosome #11. Tumor suppressor genes usually suppress the growth
of tumors and control cell growth. When altered, they no longer control cell
growth, and tumors may form.
- Beckwith-Wiedemann syndrome - this syndrome is characterized by large
birthweight and a large liver, spleen, and tongue; low blood sugar in neonatal
period, malformations around the ear, asymmetric growth of the body, abdominal
wall defects near the navel (omphalocele), and tumors of the liver and adrenal
glands. This is thought to be caused by an overactive copy of an oncogene on
chromosome #11, called IGF2. Oncogenes control cell growth, but, if mutated,
uncontrolled cell growth may result.
What are the symptoms
of Wilms tumor? The following are the most common symptoms of
a Wilms tumor. However, each child may experience symptoms differently. Symptoms
may include:
- a non-tender mass, or lump, felt or seen in the abdomen
- swelling of the abdomen
- veins that appear distended or large across the abdomen
- blood in the urine (hematuria)
- pain in the abdomen from pressure on other organs near the tumor
- decreased appetite and weakness or tiredness
- fever
- high blood pressure (hypertension)
If a tumor is suspected in the child's abdomen, it is
important not to apply pressure to this area. Careful bathing and handling of
the child is necessary before and during any tumor evaluation. Rupture of the
tumor may lead to cancer cells spreading to other tissues in the body.
These symptoms of Wilms tumor may resemble other medical
conditions or serious illnesses. Always consult your child's physician for a
diagnosis.
How is Wilms tumor
diagnosed? In addition to a complete medical history and
physical examination, diagnostic procedures may include, but are not limited to,
the following:
- abdominal ultrasound - a diagnostic imaging technique which uses
high- frequency sound waves and a computer to create images of blood vessels,
tissues and organs; can provide an outline of the kidneys, the tumor, and
determine if there are problems in the renal or other major veins in the
abdomen. It can also determine if there are any lesions or tumors in the
opposite kidney.
- abdominal computed tomography scan (Also called a CT or CAT scan.) -
a diagnostic imaging procedure that uses a combination of x-rays and computer
technology to produce cross-sectional images (often called slices), both
horizontally and vertically, of the body. A CT scan shows detailed images of any
part of the body, including the bones, muscles, fat, and organs. CT scans are
more detailed than x-rays.
- magnetic resonance imaging (MRI) - a diagnostic procedure that uses a
combination of large magnets, radiofrequencies, and a computer to produce
detailed images of organs and structures within the body. MRI can determine if
there are metastases (spreading), if there are any tumor cells in the lymph
nodes, and/or if any other organs are involved. Wilms tumors can compress other
organs in the area causing effects on their function.
- chest x-ray - a diagnostic test which uses invisible electromagnetic
energy beams to produce images of internal tissues, bones, and organs onto film.
A chest x-ray can determine if there are metastases (spreading) in the
lungs.
- blood and urine tests - to evaluate kidney and liver
function.
- biopsy - when a sample of tissue is removed and examined under a
microscope. A biopsy of the tumor to evaluate cells, extent of disease, and
diagnosis.
- surgical removal of the tumor and kidney (nephrectomy) -
surgery may be necessary for a definitive diagnosis and determining the extent
of the disease.
Treatment for Wilms
tumor: Specific treatment for Wilms tumor will be determined
by your child's physician based on:
- your child's age, overall health, and medical history
- the extent of the disease
- your child's tolerance for specific medications, procedures, or therapies
- expectations for the course of the disease
- your opinion or preference
Treatment may include (alone or in combination):
- surgery (to remove all or part of the affected kidney and any involved
structures)
- biopsy of the tumor (if the tumor is too large or involved in surrounding
structures to be removed ; a biopsy is also necessary for diagnosis and staging
the disease)
- chemotherapy (to shrink the remaining tumor, or to treat metastasis and/or
recurrent disease)
- radiation (to shrink the remaining tumor or to treat metastasis and/or
recurrent disease)
- medications (to control pain, hypertension, nausea, and infections)
- blood pressure monitoring (essential when a kidney tumor is present)
- continuous follow-up care (to determine response to treatment, detect
recurrent disease, evaluate function of remaining kidney, and manage late
effects of treatment)
Long-term outlook for
Wilms tumor: The factors for determining the prognosis and
long-term survival of children with Wilms tumor include the following:
- histology, favorable or unfavorable
- extent of the disease
- age and overall health of the child at diagnosis
- size of the primary tumor
- response to therapy
- your child's tolerance of specific medications, procedures, or therapies
- new developments in treatment
As with any cancer, prognosis and
long-term survival can vary greatly from child to child
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