Neuroscience
Brain Tumors
Overview
Types of Tumors
Causes and risk factors
Symptoms
Diagnosis
Treatments
Overview Tumors that begin
in brain tissue are called primary tumors. They are named
according to the type of cells or the part of the brain where
they begin.
When cancer spreads from another area of the body and forms
a tumor in the brain, these masses are referred to as secondary
or metastatic tumors. These are much more common than primary
brain tumors.
Brain tissue is comprised of two types of cells –
nerve cells and glial cells that surround the nerve cells
and help hold them in place. Tumors can occur in both. Others
may develop in the bone of the skull, or in the membrane that
surrounds the brain under the skull.
What is a tumor?
A tumor is an abnormal mass of tissue which develops when
the process of cell division becomes irregular. Usually, cell
division is strictly regulated: new cells are created to replace
older ones, or to perform new functions. Those cells which
are replaced die to make room for the new ones. If this balance
of cell division and death is disturbed, new cells form when
they may not be needed and old cells do not die when they
should. The extra cells form a mass of tissue called a growth
or tumor.
Irregularities in the immune system, which detects and blocks
irregular growth, can also cause tumors. Additional triggers
include genetic abnormalities, radiation, sunlight, certain
viruses, and specific toxic substances including tobacco which
causes more deaths than any other environmental agent. Certain
tumors are more common in one sex; others are seen more often
in children or the elderly; and some vary according to diet.
Tumors are divided into two broad categories: benign (not
cancerous) and malignant (cancerous).
Types of brain tumors
The brain is host to both benign and malignant tumors.
- Benign
- Not cancerous
- Usually can be removed, and seldom grows back
- Border or edge can be clearly seen
- Doesn’t invade neighboring tissue
- Unlike benign tumors in other parts of the body, they
can sometimes be life-threatening in the brain if they
press on sensitive areas
· A benign tumor very rarely becomes malignant
- Malignant
- Contain cancer cells
- Likely to grow rapidly and crowd or invade surrounding
tissue
- Generally more serious and often are life threatening
- Growth patterns
- May sometimes be encapsulated
- May grow the way a plant does, sending roots into
nearby tissue
- May shed cells that travel to distant parts of the
brain
Causes of brain tumors
The exact cause of brain tumors is not known, although medical
experts can point to risk factors. The following risk factors
are associated with developing a primary brain tumor:
- Gender – Brain tumors are more common in males than
females
- Race – Brain tumors occur more often among Caucasians
than other races
- Age
- Most brain tumors are diagnosed in people who are 35
years and older
- Brain tumors are the second most common cancer in children
- Brain tumors are more common in children younger than
8 years
- Exposure to toxins
- Radiation
- Formaldehyde
- Vinyl chloride
- Acrylonitrile (building block chemical used to make
acrylic fiber; plastics for computer and TV housings;
and rubber for oil-resistant hoses for cars and gas stations)
Symptoms
Symptoms depend on the tumor’s size, type and location.
Symptoms occur when a tumor presses on a nerve or damages
an area of the brain. Swelling of the brain and fluid build-up
within the skull also produce symptoms. The most common symptoms
are:
- Headaches (usually worse in the morning)
- Nausea or vomiting
- Changes in speech, vision or hearing
- Difficulty balancing or walking
- Changes in mood, personality or ability to concentrate
- Memory problems
- Seizures or convulsions
- Numbness or tingling in the arms or legs
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Diagnosis
Several methods are used to diagnose a brain tumor, including
personal or family medical history; physical or neurological
exam; skull x-ray; CT scan; MRI; angiogram; spinal tap; myelogram;
or biopsy.
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Treatments
The course of treatment depends on the type, location, size,
and grade of the tumor. For some types of cancer, it is also
necessary to determine if cancer cells are present in the
cerebrospinal fluid. Treating a brain tumor differs from treating
tumors in other parts of the body for several reasons:
Brain surgery requires far more precision, using highly sophisticated
instruments
The blood-brain barrier is a natural protection mechanism
that prevents many therapeutic drugs from entering the brain
The therapies used to treat the tumors as well as their
side effects are very complicated
There are a number of treatment modalities which are often
used in combination. These include surgery, radiation therapy,
chemotherapy, and immunotherapy.
Surgery
Surgery is the treatment of choice for tumors that are accessible.
The goals of surgery are to:
- Remove all, or as much of the tumor as possible
- Establish an exact diagnosis through a tissue biopsy
- Provide access for other modes of treatment such as radiological
implants or irradiating the tumor during surgery
Following a craniotomy, surgeons choose between several types
of procedures:
- Traditional surgery is performed with instruments specially
designed to remove brain tumors.
- Laser microsurgery
- May be used alone or in conjunction with conventional
methods
- The immense energy of the laser beam vaporizes the cells
- Ultrasonic aspiration
- Ultrasonic waves are used to create vibration which breaks
the tumor into small pieces
- Tumor segments are aspirated out of the brain, accompanied
by electrosurgical and sharp techniques
- Stereotactic radiosurgery
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Radiation therapy
Many tumors are radiosensitive – in other words, their
cells die quickly when exposed to radiation. For that reason,
many types of radiation therapy are now used to treat brain
tumors, including:
- Conventional radiation therapy
- Interstitial radiation (implantation of radioactive seeds
directly into a tumor)
- Intensity modulated radiation therapy (IMRT)
- Stereotactic radiation therapy
- Stereotactic radiosurgery
Chemotherapy
In chemotherapy, special chemicals are formulated to poison
tumor cells. Most are injected into a vein through an intravenous
line or a muscle, but some are given by mouth. Tumor cells
are more vulnerable to these substances than healthy cells.
Chemotherapy may be used before, during or following surgery
and radiation therapy. Often, a combination of drugs is used
in a course of chemotherapy. Chemotherapy treatments are typically
given in cycles so that a recovery period follows each treatment
session.
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Immunotherapy
Immunotherapy is a treatment program that uses biological
response modifiers (BRM) to fight tumor cells. BRMs either
kill tumor cells directly or stimulate production of other
substances by the body to control tumor growth.
Rehabilitation
Rehabilitation is a crucial element in the overall treatment
of brain tumors. Patients rely on the help of a wide range
of medical professionals, such as:
- Physical therapists – help patients regain strength
and balance.
- Occupational therapists – help patients manage activities
of daily living such as eating, toileting, dressing and
bathing.
- Speech therapists – help patients who have trouble
speaking, expressing thoughts or swallowing.
Learn more about Saint
Mary’s Neuroscience Tumor Program
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