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Malignant
or anaplastic astrocytoma is an infiltrating,
primary brain tumor, with tentacles that may invade
surrounding tissue. This provides a butterfly-like
distribution pattern through the white matter of the
cerebral hemispheres. The tumor may invade a
membrane covering the brain (the dura), or spread
via the spinal fluid through the ventricles of the
brain. Spread of the tumor (metastasis) outside the
brain and spinal cord is rare.
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These
tumors arise primarily in the cerebral hemispheres
(65 percent). Approximately 20 percent can occur in
the area of the thalamus and hypothalamus or the
diencephalon (responsible for identification of
sensation, such as temperature, pain and touch,
regulation of appetite/weight and body temperature,
as well as connecting the brainstem to the cortex).
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Most
high-grade gliomas occur sporadically or without
identifiable cause. They do however, occur with
increased frequency in families with
neurofibromatosis type I, Li-Fraumeni syndrome,
hereditary nonpolyposis colon cancer and tuberous
sclerosis. They have also been associated with
exposure to vinyl chloride and to high doses of
radiation therapy to the brain.
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Anaplastic
astrocytomas of the cerebral hemispheres and the
diencephalon, so called supratentorial anaplastic
astrocytomas, produce non-specific symptoms as a
result of increased pressure within the head, as
well as more localizing symptoms as a function of
their specific location, rate of growth and
associated inflammation.
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The
duration of symptoms is variable from a slow,
insidious onset to more abrupt presentations. The
following are the most common symptoms of an
anaplastic astrocytoma. Common symptoms may include:
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- headache
and lethargy
- symptoms
of increased pressure within the brain. These
symptoms include:
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- headache
(generally upon awakening in the morning)
- vomiting
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can occur with supratentorial high-grade gliomas
but do so less commonly than do low grade lesions
compression
of surrounding brain structures -
depending on the location of the tumor, increased
pressure can cause:
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- weakness
and other motor dysfunction
- neuroendocrine
abnormalities
- changes
in behavior or thought processes
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The
symptoms of a brain tumor may resemble other
conditions or medical problems. Always consult your
physician for a diagnosis.
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Gliomas
are heterogeneous tumors that are classified
according to their most aggressive appearing
elements. The World Health Organization
classification scheme includes 4 grades of glioma.
Anaplastic astrocytoma is a grade III tumor. It is
characterized as being of astrocytic origin but
having increased numbers of cells (hypercellularity),
abnormal cells and nuclei (cytologic and nuclear
atypia), increased proliferation of cells (mitoses)
and increased growth of blood vessels (vascular
endothelial proliferation). Anaplastic astrocytomas
are aggressive tumors that infiltrate adjacent
normal brain tissue and have a significant tendency
to spread outside of the central nervous system.
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Diagnostic
procedures for anaplastic astrocytoma may include:
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- physical
examination
- computerized
tomography scan (also called a CT or CAT scan)
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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. CT scans are more detailed than general
x-rays.
A
CT scan can assess the density of tumor tissue as
compared to normal brain as well as establish
whether the tumor exerts any the mass effect (the
effect of an additional space occupying mass
within the closed cavity of the skull on the
normal brain). Anaplastic astrocytomas most often
appear as irregularly shaped masses. When
intravenous dyes are injected, these tumors avidly
absorb dye and therefore are referred to as
enhancing lesions
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 provides greater anatomical
detail than CT scan and can better distinguish
between tumor, tumor-related swelling and normal
tissue. In addition, MRI can distinguish between
hemorrhage and tumor cyst.
magnetic
resonance spectroscopy (MRS) -
a test done along with MRI at specialized
facilities that can detect the presence of
particular organic compounds produced by the
body's metabolism within sample tissue that can
identify tissue as normal or tumor, and may be
able to distinguish between glial tumors and
tumors of neuronal origin
biopsy
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a tissue sample from the tumor will be obtained
either through a needle or by direct excision
during a surgical procedure performed by a surgeon
to confirm the diagnosis
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Specific
treatment for an anaplastic astrocytoma is
determined by the
physician based on:
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- age,
overall health, and medical history
- type,
location, and size of the tumor
- extent
of the disease
- tolerance
for specific medications, procedures, or
therapies
- how
the
doctor expects
the disease to progress
your
opinion or preference
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The
primary modes of therapy for newly diagnosed
anaplastic astrocytoma include maximal surgical
removal, when possible, followed by radiation
therapy.
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Treatment
may include (alone or in combination):
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surgery has multiple roles in the management of
anaplastic astrocytomas, including treatment of
increased intracranial pressure, biopsy and tumor
removal. For operable tumors, the extent of
surgical removal is clearly related to prognosis.
Most high-grade gliomas cannot be completely
removed because of the infiltrating fingers of
tumor which characterize their growth. However,
multiple studies have demonstrated that maximal
removal results in greater survival. Tumors of the
cerebral hemispheres are in general more easily
removed than those of the midline, diencephalic
structures. Near complete resection of anaplastic
astrocytoma in combination with radiation therapy
has been reported to produce a 5-year survival
rate as high as 40 percent, whereas incompletely
removed tumors were associated with a 20 percent
5-year survival rate. The infiltrating nature of
these tumors makes removal difficult.
Technological advances such as the intra-operative
MRI, where surgeons can visualize the tumor as
they operate with MRI scans, can enhance efforts
at resection of difficult tumors and thereby
improve survival.
radiation
therapy -
radiation therapy, which uses high-energy rays
(radiation) from a specialized machine to damage
or kill cancer cells and shrink tumors,
chemotherapy
-
a drug treatment that works by interfering with
the cancer cell's ability to grow or reproduce.
Different groups of chemotherapy drugs work in
different ways to fight cancer cells and shrink
tumors. Often, a combination of chemotherapy drugs
is used to fight a specific cancer. Certain
chemotherapy drugs may be given in a specific
order depending on the type of cancer it is being
used to treat.
While
chemotherapy can be quite effective in treating
certain cancers, the agents do not differentiate
normal healthy cells from cancer cells. Because of
this, there can be many adverse side effects
during treatment. Being able to anticipate these
side effects can help the care team, parents, and patient
prepare, and, in some cases, prevent these
symptoms from occurring, if possible.
Chemotherapy
is systemic treatment, meaning it is introduced to
the bloodstream and travels throughout the body to
kill cancer cells. Chemotherapy can be given:
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- as
a pill to swallow
- as
an injection into the muscle or fat tissue
- intravenously
(directly to the bloodstream; also called IV)
- intrathecally
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chemotherapy given directly into the spinal
column with a needle
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Side
effects in the treatment of anaplastic astrocytoma
can arise from surgery, radiation and chemotherapy.
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Surgical
morbidity, especially the production of neurologic
deficits, is minimized when procedures are performed
in specialized centers where experienced
neurosurgeons, working in the most technologically
advanced settings, can provide the most extensive
resections while preserving normal brain tissue.
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Radiation
therapy often produces inflammation, which can
temporarily exacerbate symptoms and dysfunction. To
control this inflammation steroids are sometimes
necessary.
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Some
of the chemotherapy agents are associated with
fatigue, diarrhea, constipation and headache. These
side effects can be effectively managed under most
circumstances with standard medical approaches.
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Many
specialized brain tumor treatment centers have now
added staff who are expert in complementary or
alternative medicine. These treatments including
acupuncture/acupressure, therapeutic touch, massage,
herbs and dietary recommendations can also help to
control pain and side effects of therapy.
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The
prognosis for anaplastic astrocytomas remains poor.
The best reported survival rates for radically
removed tumors treated with adjuvant radiation
therapy approaches 40 percent at five years. This is
a minority of patients, however, and most fall into
the incompletely removed category with 5-year
survival rates of less than 20 percent. The more
complete removal of hemispheric tumors may be
associated with greater survival.
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