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The term "GLIOMA" refers to a "family" of tumors, which
arise from cells known as "GLIAL CELLS". This
series of cells comprises the "glue" cells of the Central
Nervous System (CNS), in contradistinction to the
"Neurons", which are the "action" cells of the
Brain and Spinal Cord. Glial cells are the most common
cellular component of the Brain. They are five to ten times
more frequent than the trillion Brain neurons and comprise half the
Central Nervous System (CNS) by volume.
There are three (3) different cell types in this cell
series. The "Astrocyte" was so named, because it
resembles the shape of a star, when looked at under a microscope. The
next most common cell in this series is the "Ependymal Cell",
which lines the cavities of the Brain (called
Ventricles). These are normal chambers within the
Brain, where Cerebrospinal Fluid (CSF) is manufactured.
These cells are also found within the Central Canal (a small
cavity) within the Spinal Cord. The last cell type is the
"Oligodendrgogliocyte" (Oligo), which is the cell within
the Brain and Spinal Cord responsible for making the insulating
material (called Myelin), that surrounds the fibres
(axons) which transmit electrical impulses within the Brain
and Spinal Cord.
Each of these cell types is capable of forming a tumor.
The Neurosurgeons of Neurosurgical Consultants regard ALL OF THESE
AS MALIGNANT TUMORS. The degree of malignancy, and therefore,
biological aggressiveness can vary from quite indolent to extremely
aggressive. These tumors are generally categorized
according to their degree of aggressiveness, as judged by a
number of factors. Neuropathologists (specialists trained to
examine these tumors under powerful microscopes), have tended to
"grade" these tumors from 1 to 4, with "4" being the
most aggressive and "1" being the least
malignant.
An Astrocytoma is a tumor that arises from Astrocytes
which are the most numerous of the different types of Glial
Cells. Glial cells have an enormous potential for abnormal
growth and are the chief source of CNS
tumors. Approximately half (1/2) of all Primary Brain
Tumors are Glial cell neoplasms (tumors) and more than
three quarters (3/4) of all Gliomas are Astrocytomas which,
themselves, are a heterogeneous group of tumors that are grouped by
grades.
The first symptom of a Brain Tumor of any type can be a
headache, caused by increased pressure in the
Brain and therefore, inside the Skull. The headache
associated with a Brain tumor, is frequently worse in the
morning, frequently accompanied by vomiting. Other symptoms
of a Brain tumor can include seizures (Epilepsy), weakness or
numbness of a side or part of the body, or subtle symptoms
such as changes in mood, thinking or general state of well
being. Increased intracranial pressure can cause
blurred, double or lost vision.
If a patient has any of the above symptoms without any obvious
explanation, further work-up is warranted. These tumors can be
best seen by Magnetic Resonance Imaging (MRI). CT scans
can also be used; however, the quality of Brain and
tumor substance detail is best provided by MRI.
Once a mass is confirmed by any of the neuroimaging
techniques, the diagnosis needs to be established
by a biopsy of the mass. The biopsy, which is usually
carried out in conjunction with a more definitive surgical excision,
will help differentiate tumor from other types of masses, such
as infection. The microscopic structure of the tumor is vitally
important in the pathologist's "grading" of the tumor.
Tumor grading is important for prognosis and therapy.
Tumors are graded by microscopic examination of the tumor
specimen. The specimen is evaluated for the most
malignant components. Varying "grades" of tumor cells can be found
in any one tumor. The biological behavior of the tumor will relate to
the highest grade (worst and most aggressive) component of that
tumor, even though that higher grade component comprises a small
portion of the entire tumor. In other words, if a tumor
is 99.5 % Grade 1 and only ˝ percent Grade 3 or 4, the biological
behavior of that tumor, will be as if the entire tumor is Grade 3 or
Grade 4.
Astrocytomas are neither histologically or biologically
uniform tumors. The borderline between low-grade (i.e.
"non-aggressive) and Anaplastic (Malignant) Astrocytoma,
can be quite indistinct. Although many patients with
low-grade Astrocytomas survive for extended periods, 50%
of surgically treated lesions evolve into Anaplastic
Astrocytomas or Glioblastomas. Degeneration into a higher-grade
neoplasm is the most common cause of death in patients with low-grade
Astrocytomas.
Low-grade Astrocytomas are uncommon tumors and
occur less frequently than their more malignant
counterparts. They are generally found in a younger
population and have a more favorable prognosis.
Their true incidence is difficult to determine, because sampling and
grading vary substantially. Low-grade Astrocytoma probably
represents 10% to 15% of Gliomas. These are
neoplasms of children and adults from 20 to 40 years of age. These
tumors are rare in older adults. Low-grade Astrocytomas can
present with any of the symptoms previously described.
Surgery is important in order to remove the mass effect and
pressure caused by the tumor. However, surgery is
rarely curative for most infiltrating hemispheric Gliomas,
unless the tumor is located at the anterior (front) portion of
either a Temporal or Frontal Lobe.
Surgery is the principal treatment in the following situations
of low-grade Astrocytomas:
- Childhood Cystic Cerebellar Astrocytomas.
- Supratentorial Pilocytic Astrocytomas.
- Large tumors, or tumor cysts, causing severe pressure on the surrounding Brain.
- Obstruction of Cerebrospinal Fluid (CSF) flow.
- Seizure control for Epilepsy that is refractory to medical therapy.
Radiation Therapy is the primary non-surgical treatment.
Radiation can be administered to the whole Brain, or it can be
relatively focused to a region of the Brain. Radiosurgery
(Focused Beam Radiation) allows for very precise focusing
of radiation beams into the area of Astrocytoma involvement,
with less risk for damaging the surrounding Brain.
Unfortunately, the energy from radiation is destructive to
normal Brain cells, as well as, abnormal tumor cells.
In cases of incomplete removal of ordinary low-grade
Astrocytomas, post-operative radiation is probably indicated.
Consideration to WITHHOLD Radiation Therapy may be
appropriate in cases of apparent gross total surgical removal,
or incomplete removal, in cases of Pilocytic Astrocytoma
or Cystic Cerebellar Astrocytoma. Meticulous follow up is
required, since Radiation Therapy can be helpful where tumor
recurrence or progression is documented.
Chemotherapy is usually not offered for patients
with a low-grade Astrocytoma. Nevertheless, it may
become appropriate if any progression of the tumor is subsequently
noted.
Anaplastic Astrocytomas are among the most common
Primary Malignant Brain Tumors. These tumors represent
approximately one third of all Astrocytomas and about
one quarter of all Gliomas. They occur at any age
but typically are found in older patients. Their peak
incidence is in the fifth and sixth decades of life.
Malignant Astrocytomas generally have a poor prognosis,
with an average survival of two (2) years. Both types of
malignant Glial tumors (Anaplastic Astrocytomas and Glioblastomas)
spread through the extracellular space and along the compact white
matter tracts that connect each part of the Brain with every other
part of the Brain.
Seizures and focal neurological deficits are common
presenting symptoms. In addition, any of the symptoms described
previously, may be present at the time of diagnosis.
MRI Scan is the single most useful Neuroimaging study. It
provides detailed information about the size, location and gross
architectural features of these tumors as well as identifying
the extent of Cerebral Edema (swelling) and effect upon the
surrounding Brain tissue.
Surgery to reduce the bulk of the tumor, followed by Radiation
Therapy, has become the standard against which other treatments are
compared. One must consider that these tumors cannot
usually be cured with surgery alone, although the
Neurosurgeons of Neurosurgical Consultants are encouraged by their
increasing experience with long term survival using a combination
of aggressive approaches. The goals of treatment, if "cure"
is not possible, should be to prolong survival, together with a higher
quality of life.
Because of the infiltrative nature of Astrocytoma,
it is unlikely that surgery will ever be the single definitive
treatment for these neoplasms. However, increasingly
safe and aggressive tumor resection is possible with the advent of
technological advances such as intra-operative MRI and Ultrasonic
imaging systems, as well as, actual tumor-brain interface
"visualization", using Fluorescence-guided resection
techniques..
FLUORESCENCE is one of the most advanced concepts for the
surgical management of an infiltrative Brain tumor and the ONLY METHOD
that permits the Neurosurgeon to visually identify the tumor that
infiltrates Brain tissue. This technique (developed primarily in
Europe) involves the ingestion of a medication (5-aminolevulinic acid
or "ALA" dissolved in water) that is taken up in certain molecules
of the tumor which when subjected to a special violet-blue light
beamed through the Neurosurgical Operating Microscope actually
("lights up") glows.
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The Neurosurgeons of Neurosurgical Consultants firmly believe that
aggressive resection of the tumor, is the first definitive step in the
treatment of these tumors. Other steps include Chemotherapy and
Radiation Therapy. Some additional technologies have also helped to
improve their outcomes. For example,
it is now possible to grow cultures of the
tumor and subject these in the laboratory to sensitivity testing
against various chemotherapy agents prior to initiating Chemotherapy
in a clinical setting.
Traditional management has been to use "standard" forms of
chemotherapy. Currently there are some unconventional
chemotherapeutic alternatives that offer considerable hope for
improved quality and length of survival. New therapies such as
Temodar (temozolamide), Avastin (bevacizumab which is an
anti-angiogenesis medication) and CPT-11 are currently being
used by one of our
Neuro-oncologists.
Preliminary results have been encouraging. The reader may wish to view
the
"Virtual Trials"
website for additional information.
In some tumor cases we choose to place a special chamber called an
"Ommaya Reservoir" under the scalp, with an attached catheter
residing in the "bed" of the tumor, after resection has been completed.
This permits the Neuro-oncologist to instill chemotherapeutic
medications directly into the tumor bed. This is a far more
effective methodology than placing "chemotherapy wafers in the tumor
bed.
Radiation therapy continues to have an important place in the
treatment of many of these tumors. Refinements have been made that
make this treatment less toxic than in previous years.
GBMs are the most common and most malignant of the
primary CNS neoplasms, representing 15% to 20% of these
tumors. Approximately half of all Astrocytomas are GBMs.
GBM is the most common supratentorial neoplasm in adults.
GBMs usually occur in patients over 50 and are unusual in
patients under 30. Like Anaplastic Astrocytomas, GBMs
can occasionally be found at any age; Anaplastic Astrocytomas and
GBMs are among the four most common primary Brain tumors in
infants and children under 2 years of age.
Various symptoms occur with GBM, including seizure, focal
neurological deficits, and stroke like syndromes.
The first symptom of a Brain tumor of any type can be a
headache, since these tumors act as masses within the boney
skull and thus cause increased pressure in the Brain. The headache
associated with a Brain tumor, is frequently worse in the
morning and is accompanied by vomiting. Other symptoms of a
Brain tumor can include seizures, weakness or numbness of a side
or part of the body, or such subtle symptoms such as changes in mood,
thinking or general state of well being. Sometimes increased pressure
in the Brain can cause blurred, double, or lost vision.
If a patient has any of the above symptoms, without any obvious
explanation, further work-up is warranted. These tumors can be
seen best by Magnetic Resonance Imaging (MRI) since the degree
of detail is much greater than that provided by CT scans. As with
other tumors and most particularly with any of the Gliomas, once
a mass is confirmed by any of the imaging techniques, the diagnosis
needs to be established by a biopsy of the mass. THE BIOPSY IS
USUALLY DONE IN CONJUNCTION WITH AGGRESSIVE RESECTION OF THE
TUMOR. The biopsy identifies the particularities of the tumor and
differentiates it from other types of masses, such as infection.
Along with primary CNS Lymphoma, GBMs have the worst prognosis
of all primary brain tumors. GBMs disseminate early, rapidly, and
widely. Central Nervous System spread is common, but distant
metastasis is rare.
In selecting the treatment of High Grade Malignant
Astrocytomas, it should be kept in mind that the following
three (3) statistically independent factors affect the length of
survival: 1) age at the time of diagnosis, 2) histological features
(Grade of the tumor and additional characteristics such as Mitotic
Index), and 3) performance status (the level of the patient's
neurological capabilities).
Older patients with high grade malignant Brain tumors, who are
in poor neurological condition at the time of surgery, do less
well.
The primary initial therapy is to gain control of the
increased Intracranial Pressure (ICP). Often times, these
patients have significant Brain swelling, in addition to the
presence of and as a consequence of the tumor. Pre-treatment with a
course of high dose intravenous steroids, may well improve the
condition of the patient prior to surgery. In some cases, this
may mean a strategic delay of surgical intervention for
three (3) to seven (7) days. The wait can be rewarded by a far
better initial outcome.
Aggressive surgical excision of the tumor is advocated in most
patients. The goal is to reduce the maximum amount of the tumor. In
some cases this may mean an extensive Frontal or Temporal Lobectomy.
When tumor is within the middle or posterior portions of the Temporal
lobe, the Parietal or Anterior or Middle Occipital Lobe, an aggressive
internal decompression of the tumor is warranted.
It is imperative to understand that there are surgical
limitations in the removal of these "infiltrative" tumors because they
"spread" along the interconnecting fiber pathways (tracts) of the
Brain. As such, these tumors can rarely be entirely removed
surgically.
There are some advanced technologies that currently assist in the
extent of resection. The ability of the surgeon to "visualize" tumor
is somewhat limited. Magnification of vision, Intraoperative
ultrasound imaging, Intraoperative MRI scanning and Intraoperative
Fluorescence techniques (See Below) are a few of the
adjunctive technologies that may be available to assist maximum
resection, while limiting the risk of injuring adjacent functioning
Brain.
FLUORESCENCE is one of the most advanced concepts for the
surgical management of an infiltrative Brain tumor and the ONLY
METHOD that permits the Neurosurgeon to visually identify the tumor
that infiltrates Brain tissue. This technique (developed primarily in
Europe) involves the ingestion of a medication (5-aminolevulinic acid
or "ALA" dissolved in water) that is taken up in certain molecules
of the tumor which when subjected to a special violet-blue light
beamed through the Neurosurgical Operating Microscope actually(
"lights up") glows. Once "seen" under the Neurosurgical Operating
Microscope, the surgeon can remove the fluorescent portion by using
any of several methods.
The Neurosurgeons of Neurosurgical Consultants firmly believe that
aggressive resection of the tumor, is the first definitive step in the
treatment of these tumors. The surgeon may choose to reserve
a small part of the tumor for tissue culture in the laboratory
followed by sensitivity testing against various chemotherapeutic
agents. It can be helpful to know beforehand, if a
certain drug has any or limited effectiveness against this particular
tumor, in this particular patient. These additional technologies
have helped to improve outcomes. We now routinely culture the tumor
and subject it to sensitivity testing against various chemotherapy
agents prior to initiating Chemotherapy.
Radiation therapy continues to have an important place in the
treatment of most of these patients and is the standard adjunct
therapy against which other treatments are compared.
Refinements have been made that make this treatment less toxic than
in previous years. For most patients, this will be the second major
treatment option, in a comprehensive therapeutic program.
Chemotherapy is the third arm of this comprehensive effort
to prolong and maintain a high quality of life. Traditional
management has been to use "standard" forms of chemotherapy. Currently
there are some unconventional chemotherapeutic alternatives that
offer considerable hope for improved quality and length of
survival. One of our
Neuro-oncologists
has utilized these newer medications such as Temodar
(temozolamide), Avastin (bevacizumab, an anti-angiogenesis agent) and
CPT-11, either alone (or more commonly) in combination or with
other drugs, to produce encouraging results. Additional information
regarding these treatments is available at the
"Virtual Trials".
In some tumor cases we choose to place a special chamber called an
"Ommaya Reservoir" under the scalp, with an attached catheter
residing in the "bed" of the tumor, after resection has been
completed. This permits the Neuro-oncologist to instill
chemotherapeutic medications directly into the tumor bed. This
is a far more effective methodology than placing "chemotherapy wafers
in the tumor bed.
There are several treatment concepts that have considerable interest.
Perhaps the most attractive is the potential availability of Gene
Therapy to treat Astrocytomas. Another very attractive
"surgical" application involves the selective susceptibility of
malignant tumor cells to beamed lasers. When this is
combined with "Fluorescence-guided" technologies, the surgical
management will be dramatically altered.
The following information at WebMD.com may also be useful:
Brain tumors, adult: Treatment - Health Professional Information (NCI PDQ) - General Information
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This page last edited on 5/17
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