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Overview
A tumor is the abnormal,
spontaneous growth of new tissue. Tumors are
either benign, noncancerous tumors that do not
spread to other tissues or parts of the body or
malignant, cancerous tumors that invade other
tissues and parts of the body. Benign tumors and
cancerous tumors that exist where the cancer
originated are referred to as primary tumors. On
the other hand, if a cancerous tumor exists in the
brain, for example, but the original cancer
developed somewhere else in the body, then the
brain tumor is called a metastatic tumor. Any of
these kind of tumors can develop in either the
brain or spinal cord, although spinal cord tumors
are rare.
More than 100,000 Americans are
diagnosed with a brain tumor every year, and the
numbers are increasing. We don't know what causes
brain tumors, so we do not know how to prevent
them. Because of the incredible complexity of the
human brain and its role in the normal functioning
of the human body, brain tumors often have
incapacitating consequences. Surgery and radiation
are the normal treatments, although their
effectiveness is limited by the risk of damaging
healthy brain tissue.
About 44% of all primary brain
tumors are benign. But even benign tumors can
recur after they have been removed, and they can
cause death, unlike benign tumors in other parts
of the body that are generally harmless.
Malignant brain tumors are the
second leading cause of cancer death in young
adults (under the age of 34), young children
(under the age of 15), and people over 65. There
is no known behavioral risk, so there is no way to
educate people about what they can do to minimize
their chances of developing brain cancer.
Symptoms
A tumor is a mass of cells that
grows over time and expands inside the brain. This
expansion causes two general types of symptoms:
increased pressure inside the head (intracranial
pressure) and disrupted brain function. The
increased intracranial pressure can result from
the growing tumor itself, swelling associated with
metastatic tumors, or hydrocephalus (a swelling
caused by the accumulation of too much
cerebrospinal fluid) obstructing the normal flow
of cerebral spinal fluid. The common symptoms that
patients notice are headache, nausea and vomiting,
general confusion and lethargy. When the function
of the brain is disrupted by localized problems
associated with a tumor, symptoms include
seizures, speech and language problems, visual
problems, or general weakness. The particular
symptom often reflects where in the brain the
tumor is located.
The various symptoms of
neurological dysfunction occur no matter how
slowly or quickly the tumor grows. In slow-growing
tumors, however, the brain can sometimes
accommodate for the growth of the tumor, and the
symptoms may be less pronounced. When the tumor
grows rapidly, the symptoms may occur very
suddenly and intensely. The most common symptoms
of a brain tumors include particular kinds of
headache, seizures (especially in adults who have
never experienced seizures before), nausea and
vomiting (especially when it's coupled with
another symptom), a change in cognitive abilities
(ability to perceive, reason and remember), and a
wide range of neurological abnormalities depending
on where in the brain the tumor is located.
Headaches
A new pattern or type of headache is the first
noticeable symptom for about 20% of all people
with brain tumors. Eventually, headaches will
occur in over 60% to 70% of all patients at some
point in the course of their illness. The headache
often is on the same side of the tumor but may be
located anywhere on the head. Many headaches
associated with brain tumors tend to be located on
the frontal areas of the head (forehead/top of
head). This happens not because the tumor is there
but rather that is where the pain is referred
(referred pain is pain that is felt somewhere
different from where it originates).
Headaches caused by brain tumors
are usually nonthrobbing and worse in the morning
after laying flat all night, because pressure in
the brain increases when the head is down. They
may be worse with exertion. Most patients describe
nausea and vomiting with the headache. If the
tumor is obstructing the ventricles, the
structures that contain the cerebrospinal fluid,
the headache may get worse when a person changes
position.
Seizures
A seizure is a sudden, brief attack of
uncontrolled motor activity or altered
consciousness. Seizures occur in approximately 35%
of all brain tumor patients. The probability of
having a seizure depends on the location of the
tumor, as some parts of the brain are more prone
to seizure activity than others. Some seizures may
be partial, and involve only a single site in the
brain. Others can affect the whole brain and
result in loss of consciousness.
Nausea and Vomiting
When a person develops a new pattern of headaches
in the morning coupled with vomiting, they should
be further evaluated for the presence of a brain
tumor. Even if this particular pattern doesn't
develop, many people with brain tumors eventually
develop chronic nausea and loss of appetite, which
are presumably associated with the increased
intracranial pressure (pressure within the skull
compartment).
Change in Cognitive Status
Patients with tumors often develop early changes
in their cognitive abilities. These include
difficulties remembering things, changes in
personality or mood, lack of initiative, and poor
judgement. Depending on where the tumor is
located, a person may have reading, writing or
speaking difficulties. It may be very difficult
for some folks to engage in abstract reasoning,
and some people may not be able to make decisions.
Many people with brain tumors suffer from sleep
disorders and restlessness and are unable to
concentrate.
Motor and Sensory Abnormalities
The specific neurological abnormalities that a
person with a brain tumor experiences vary from
person to person and depend on where in the brain
the tumor is located. For example, if the tumor
invades the motor regions of the brain (areas
responsible for movement of the skeletal muscles,
such as those in the arms and legs), patients can
show signs of motor weakness on the opposite side
of the body (one side of the brain controls the
opposite side of the body). The arms and legs on
the opposite side of the body may be stiff or move
awkwardly.
When the areas of the brain
responsible for sensing the environment - the
sensory structures - are damaged, a person may
feel tingling, numbness, or other odd sensations.
People may not be able to recognize parts of their
environment. For example, if the tumor obstructs
the visual pathways, in addition to vision loss,
patients may not be able to recognize objects by
looking at them. If the tumor is in the temporal
lobe of the brain, a person may see hallucinations
or experience other unusual perceptions. If the
tumor is in the frontal lobe, a patient may have
bowel and bladder problems.
Types
There are two types of brain
tumors: primary brain tumors that originate in the
brain, and metastatic brain tumors that originate
from cancer cells that have come from other parts
of the body. Primary tumors can be either benign (noncancerous)
or malignant (cancerous). Malignant tumors in the
brain are life-threatening, because of their
aggressive and invasive nature. Even slow-growing
benign tumors in the brain can have
life-threatening consequences though, depending on
the type of tumor and where in the brain it is.
This is because the skull is a closed container,
and when brain tumors take up space they compress
the vital tissues and structures around them,
causing serious neurological problems. Some brain
tumors are easier to remove and treat than others.
Brain tumors are classified
according to the type of cell that makes up the
tumor, or the cell type from which the tumor
originated. Gliomas are tumors that are made up of
glial cells (cells that provide important
structural support for the nerve cells in the
brain). An astrocyte is one type of glial cell,
and the tumors that grow out of astrocytes are
called astrocytomas. Meningiomas are tumors of the
meninges, the membranes covering the brain.
Pituitary adenomas are tumors that start in the
anterior pituitary; the pituitary gland is a gland
at the base of the brain that secretes hormones
important for growth and reproduction. Lymphomas
are tumors made up of lymph cells; lymph is a
fluid that flows through all the tissues of the
human body and plays an important role in cleaning
out bacteria and other foreign matter. Metastic
tumors are brain tumors that have originated
elsewhere in body and have metastasized to the
brain. In addition to being classified on the
basis of cell type, malignant tumors are typically
assigned a tumor grade, based on what the cancer
cells look like under a microscope.
Primary Brain Tumors
Gliomas
Gliomas are tumors that are made up of glial
cells, cells that play an important structural
role in the brain. There are several types of
gliomas, the two most common being astrocytomas,
cancerous tumors, and oligodendrogliomas - rare,
usually benign tumors. A particularly malignant
type of astrocytoma is known as a glioblastoma
multiforme, which can be either low grade
(slow-growing and not very aggressive) or high
grade (fast-growing and very aggressive).
Astrocytomas  About
25% of all brain tumors are astrocytomas,
malignant tumors that originate in cells called
astrocytes. Astrocytomas are graded and named
based on what the cells look like under the
microscope. Low-grade astrocytomas are made up of
the least aggressive cancer cells, anaplastic
astrocytomas are made up of more aggressive cancer
cells, and a glioblastoma multiforme is a type of
astrocytoma that is made up of the extremely
aggressive cancer cells. Glioblastoma multiforme
is the most common adult primary tumor.
Astrocytomas usually develop
between the ages of 20 to 50, but they can occur
at any age. One of the most common early symptoms
is seizures. Although they can develop anywhere in
the brain, they usually develop in the temporal or
frontal lobes of the brain and then spread into
the adjacent tissues.
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Glioblastoma Multiforme
- Glioblastoma multiforme, a type of malignant
astrocytoma, are the most common adult primary
brain tumors. They occur slightly more
frequently in men. Patients with these types of
tumors are usually over the age of 50, but the
tumors can develop at any age. Patients who
develop the tumor at a younger age have a
significantly better survival rate than older
individuals. Symptoms are caused by rapid tumor
growth, infiltration into adjacent tissues,
edema (swelling) and an increased accumulation
of cerebrospinal fluid in the brain
(hydrocephalus). Most people experience
headaches, seizures, or a change in their mental
status.
Oligodendrogliomas Less
than 5% of all brain tumors are oligodendrogliomas,
tumors that originate in cells called
oligodendrocytes. The average age of patients with
these kinds of tumors is around 40 years old.
Oligodendrogliomas are very slow-growing, usually
benign tumors (less than 10% are malignant), and
they occur most often in the frontal lobes. The
first symptom for many patients is a seizure.
There are two types of
oligodendrogliomas: low-grade oligodendrogliomas
are made up of less aggressive cells, and
anaplastic oligodendrogliomas are made up of more
aggressive cells. More common than either
low-grade or anaplastic oligodendrogliomas,
however, are tumors made up of a mix of
oligodendrioglioma and astrocytoma. These
mixed-cell tumors are called oligoastrocytomas.
Ependymoma Less
than 5% of all brain tumors are ependymomas, which
usually occur in the lining of the ventricles, the
structures in the brain that contain the
cerebrospinal fluid. They also occur in the lining
of the middle part of the spinal cord. One of the
earliest symptoms is hydrocephalus, an increased
accumulation of cerebrospinal fluid that causes
swelling and neurological dysfunction.
Pituitary Adenomas
The pituitary gland is a small structure at the
base of the brain that produces hormones necessary
for normal growth and metabolism. Tumors in the
pituitary gland are called pituitary adenomas,
benign tumors that account for about 10% to 20% of
all brain tumors.
There are two types of pituitary
adenomas: secreting and nonsecreting. A person
with a secreting pituitary adenoma has abnormally
high levels of pituitary hormones circulating
through their body, which in turn causes a range
of symptoms from impotence to amenorrhea (the
abnormal ending of menstruation). For example, one
of the more common types of pituitary adenomas
produces and secretes excess prolactin, a
substance responsible for triggering milk
production when a woman is nursing.
In addition, because the pituitary
gland is located near important visual pathways, a
person with a pituitary adenoma may lose some or
all of their vision.
Meningiomas
The meninges is the thin outer covering that lines
the spinal cord and brain. It is made up of three
layers: the dura matter (external), the arachnoid
(middle) and the pia matter (internal). Tumors
that originate in the meninges are called
meningiomas.
About 15% to 20% of all brain
tumors are benign, slow-growing meningiomas. Even
though they are benign, they can still lead to
severe neurological dysfunction. Patients often
suffer seizures, headache, weakness, and visual
problems. They occur more commonly in women and
after the age of 40. Patients with
neurofibromatosis, a genetic disorder that
predisposes to certain types of tumors, are at a
greater risk for developing meningioma. Patients
who have had previous brain radiation are also at
a greater risk for developing meningioma. Many
patients with meningiomas seem to have a genetic
defect on chromosome number 22.
Nerve Sheath Tumors (Schwannomas)
Nerve sheath tumors, also known as schwannomas,
are tumors that originate in the Schwann cells
that make up the protective sheath that surrounds
the nerve fibers. Schwannomas are usually benign
and slow-growing. One of the most common types is
known as a vestibular schwannoma, or acoustic
neuroma. Another common schwannomas causes facial
paralysis.
Acoustic Neuromas Acoustic
neuromas are schwannomas that involve the eighth
cranial nerve. There are a total of 12 pairs of
cranial nerves that originate in the brainstem
(the bottom part of the brain that connects to the
spinal cord) and lead to various parts of the face
and neck. The eighth cranial nerve is responsible
for balance and hearing. Acoustic neuromas cause
early hearing loss in the ear on the side of the
tumor, tinnitus (ringing in the ears), vertigo
(dizziness), balance problems, and facial
weakness. These tumors occur most commonly in
people between 30 and 50 years old but can occur
anytime.
Metastatic Brain Tumors
Cancerous tumors that spread to the brain from
other parts of the body, such as the lung, are
said to be metastatic. Tumor cells spread to the
brain through the bloodstream. In more than half
of all metastatic brain cancer, the tumors are
found throughout the brain and are not localized
to one particular spot, making them extremely
difficult to treat. Between 20% to 40% of all
cancer patients develop metastases to the brain.
In adults, the most common types of cancer to
spread to the brain are lung, breast,
gastrointestinal, and urinary/genital tract
cancer, as well as malignant melanoma.
The main symptoms of metastatic
brain tumors include seizures, headaches, weakness
and confusion. In general, the prognosis for
patients who develop brain metastases is poor.
Spinal Cord Tumors
Primary spinal cord tumors are very rare and
usually benign. Only about 1 in 200 newly
diagnosed tumors are spinal cord tumors. Of these,
less than 3% are malignant, or cancerous. Spinal
cord tumors are made up of the same types of cells
that make up brain tumors. For example, they
include meningiomas and gliomas. Most malignant
spinal cord tumors, again of which there are very
few, are tumors that originate from cancer cells
that come from other parts of the body.
The spinal cord has only a limited
amount of space inside the spinal column (the
backbone or spine), so even a very small tumor can
cause enough pressure to become problematic.
Though sometimes the tumor grows so slowly that
the spinal column is able to adapt to it and make
room for it such that a person suffers very few
symptoms. Very aggressive metastatic spinal cord
tumors can cause paralysis very quickly - even
within days. Slow-growing tumors can also cause
paralysis if left untreated.
Surgery is the usual course of
treatment for primary spinal cord tumors.
Metastatic spinal cord tumors are not always
treated surgically, however, especially if there
is more than one metastasis. Although often
surgery may be used as a way to relieve pain and
other symptoms, even though it may not actually
involve removing the tumor.
Treatment
Treatment for brain tumors involves
any combination of surgery, radiation
and chemotherapy.
The first goal of treatment is to remove as much
of the tumor as possible, without doing damage to
the surrounding normal brain tissue. Even if two
patients have an identical tumor, their treatment
may be different. Various factors such as age,
general health, occupation, and a person's
personal choice, all play a role in determining a
course of treatment. Some tumors can be treated
surgically, whereas others cannot. Sometimes there
are several different surgical procedures for a
particular type of tumor. Sometimes a tumor can be
treated with radiation alone and does not need to
be surgically removed. Oftentimes a
multidisciplinary team of medical specialists will
work together to contribute to a patient's
treatment.
Surgery
For all patients undergoing brain tumor surgery,
it is important that certain tests be done
beforehand to allow for the safest possible
surgery. All patients should be in generally
stable medical condition. Patients over 40 should
have an EKG and chest X-ray, as well as several
other tests to evaluate factors such as
hypertension and diabetes. If a person has
uncontrolled hypertension or diabetes, or their
blood exhibits anticoagulation, or if they have
active coronary ischemia, surgery should not be
done.
Brain tumor surgery is used both
for diagnosing and treating a tumor. Complications
arise in less than 5% of all brain tumor surgeries
and depend on where exactly the tumor is located
and what type of tumor it is. Major complications
include infection, seizures, decreased neurologic
capabilities, bleeding, and leaking of
cerebrospinal fluid. Most brain tumor surgeries
involve temporarily removing the bone and opening
the dura (the outer membrane that covers the
brain) and then removing the tumor and replacing
the bone. The tumor may be completely removed, if
it's a low-grade astrocytoma, a single metastasis,
easily removable meningiomas, vestibular
schwannomas, most parts of a pituitary adenoma,
and other various benign tumors; or it may only be
biopsied or resected, as with high-grade gliomas,
lymphomas.
New surgical techniques include stereotactic biopsy or
surgery that use computer guidance to
exactly locate and either biopsy or remove the
tumor, endoscopic surgery, laser surgery,
and surgery under local
anesthesia.
Stereotactic Surgery The
word stereotaxic comes from Greek and Latin words
meaning "three dimensions" and "to touch." This
technique utilizes CAT scanning and MRI imaging of
the brain to help find the exact location of the
tumor. A special frame is placed on the patient's
head and only a very small hole is drilled through
the skull. Stereotactic surgery reduces the rates
of complications normally associated with
performing an open resection (cutting or removing
a tumor) in the brain, which involves cutting a
wide opening in the skull. With computer guidance,
the neurosurgeon is able to operate very
precisely.
Endoscopic Surgery Endoscopic
surgery is a type of surgery used to remove
pituitary adenomas. In the past, pituitary
adenomas were removed by making an incision in the
mouth, beneath the upper lip, and then using a
microscope to look up through the tissue to the
base of the skull where the pituitary gland is
located. With an endoscope, the tumor can be
removed without any incision at all. Instead, the
surgeon goes through the nose and is able to reach
and remove a tumor in the pituitary gland through
nasal channels that already exist and don't need
to be cut. It is a less painful procedure than the
more traditional surgery and has a quicker
recovery time. Other tumors that are at the base
of the skull can also be removed using endoscopic
surgery.
Laser Surgery The
use of lasers (light amplification by stimulated
emission of radiation) allows a surgeon to remove
diseased tissue by aiming a beam of concentrated
light on it rather than using a scalpel to cut it
away. It is often used following surgery to remove
any residual tumor tissue.
Surgery under Local Anesthesia Surgery
under local anesthesia involves the use of brain
mapping techniques. A brain mapping technique that
allow a surgeon to operate in sensitive areas of
the brain, such as those that control motor
function or speech. Small electrodes can be used
to stimulate specific pathways so that the nerve
response can be measured and a surgeon can
determine the function of the nerve. The patient
is awake during surgery.
Postoperative Care
Postoperative care includes drug therapy with
corticosteroids, histamine inhibitors (blocking
stomach acid), and antiepileptics. Sometimes
patients may need to visit a postoperative
rehabilitation facility. Corticosteroids (dexamethasone
and Decadron) help reduce swelling and can relieve
various postoperative neurological effects.
Radiation Therapy
Most malignant brain tumors are treated with
external-beam radiation even if the entire primary
tumor is surgically removed, because often there
are hidden tumor cells still left in the brain
tissue. For benign tumors, radiation is usually
applied when the entire primary tumor cannot be
surgically removed. Some benign tumors are treated
with external-beam radiation to prevent
recurrence, even if the entire primary tumor has
been surgically removed. Or, they may be treated
with radiation at the time of recurrence. For
malignant tumors, radiation more than doubles the
survival rate for patients with anaplastic
astrocytomas and glioblasoma multiformes, and it
can prolong survival for patients with low-grade
gliomas.
External Beam Radiation External
beam radiation is the traditional form of
radiation therapy. It delivers radiation from
outside of the body, usually a couple of weeks
following surgery. It is typically applied at
regular intervals for several weeks.
Hyperfractionation is a modified form of external
beam radiation that involves applying less intense
but more frequent doses of radiation, to which
some patients respond more readily.
New Types of Radiation Therapy:
Stereotactic Techniques New
types of radiation that are being used to treat
brain tumors include stereotactic radiosurgery or
radiotherapy, as well as brachytherapy.
Stereotactic radiosurgery involves using focused
radiation on a localized spot in a single dose.
Even though it is called "radiosurgery," it does
not involve actual surgery. A head frame, to which
a CT or MRI scanner is attached, is attached to a
person's skull, and with the aid of the computer
imaging, the radiologist is able to pinpoint the
tumor and aim the radiation directly at it.
There are new stereotactic
techniques that do not involve the use of the head
frame. Often the radiation comes from several
different directions and hits the tumor at various
angles. The advantage of such localized radiation
is that the surrounding, healthy tissue is left
undestroyed. It is often used in addition to
external beam radiation, especially for malignant
gliomas and mestastases that are in deep or
sensitive areas of the brain where surgical
removal is potentially dangerous. Some tumors,
however, cannot be treated with such intense local
radiation. The optic nerves are especially
sensitive to radiation, so tumors near the optic
nerves are better treated with several small doses
rather than one big blast. Stereotactic
radiotherapy involves applying many small doses of
radiation to a local spot, using the same imaging
techniques that stereotactic radiosurgery
requires. Brachytherapy involves implanting
capsules that contain radioactive substances into
the tumor.
There are various other radiation
techniques, some of which are being used on an
experimental basis. There are an assortment of
other technologies, as well as the use of
medications or other compounds that may make tumor
cells more sensitive to radiation.
Chemotherapy
Chemotherapy is not used for benign tumors and is
generally not a very helpful treatment for most
malignant brain tumors. Most tumors are
satisfactorily treated with radiation and/or
surgery. For those that aren't, the problem with
chemotherapy is that it works by interrupting
mitosis, the process of cell division. Many brain
tumors are already slow-growing, so slowing down
the process of their growth and division by
chemotherapy doesn't do much good. Another problem
with using chemotherapy to treat brain tumors is
finding or developing drugs that effectively cross
through the blood-brain barrier and get to the
place in the brain where they need to be in order
to do any good. One drug that has proved to be
effective is BCNU. A new technique enables
neurosurgeons to place a wafer soaked with BCNU
into the surgical cavity after the tumor has been
removed. By applying it directly to the tumorous
region of the brain, side effects are limited and
the drug has a more beneficial effect. Some tumors
are treated by injecting drugs directly into the
spinal fluid.
Although, overall, studies have
shown that patients who receive chemotherapy for
malignant tumors show improved survival compared
to people who do not receive the chemotherapy. The
effectiveness of chemotherapy depends on the tumor
type (medulloblastomas, anaplastic astrocytomas
and glioblastomas respond to varying degrees to
certain drugs). Chemotherapy is often used in very
young children to delay radiation therapy as long
as possible. Some meniongiomas respond to
anti-progesterone agents. Most mestastatic brain
tumors do not respond to chemotherapy, although
there are exceptions. With metastatic brain
tumors, the best chemotherapy agent is usually the
one that has been the most effective with the
primary cancer.
There are many experimental
treatments, ranging from novel chemotherapy agents
to drug therapy to new ways of applying radiation,
that your neurologist, neurosurgeon, radiation
oncologist or neurooncologist can tell you about.
As with any serious illness, it is generally a
good idea to get a second or third opinion and
gather as much information as you can about your
particular case and what your options are.
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