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Brain Tumor

Brain Tumor

Definition

A brain tumor is an abnormal growth of tissue in the brain. Unlike other tumors, brain tumors spread by local extension and rarely metastasize (spread) outside the brain. A benign brain tumor is composed of non-cancerous cells and does not metastasize beyond the part of the brain where it originates. A brain tumor is considered malignant if it contains cancer cells, or if it is composed of harmless cells located in an area where it suppresses one or more vital functions.

Description

Each year, more than 17,000 brain tumors are diagnosed in the United States. About half of all primary brain tumors are benign, but in life-threatening locations. The rest are malignant and invasive.

Benign brain tumors

Benign brain tumors, composed of harmless cells, have clearly defined borders, can usually be completely removed, and are unlikely to recur. Benign brain tumors do not infiltrate nearby tissues but can cause severe pain, permanent brain damage, and death. Benign brain tumors sometimes become malignant.

Malignant brain tumors

Malignant brain tumors do not have distinct borders. They tend to grow rapidly, increasing pressure within the brain (IICP) and can spread in the brain or spinal cord beyond the point where they originate. It is highly unusual for malignant brain tumors to spread beyond the central nervous system (CNS).

Primary brain tumors

Primary brain tumors originate in the brain. They represent about 1% of all cancers and 2.5% of all cancer deaths.

KEY TERMS

Central nervous system (CNS) The division of the nervous system that consists of the brain and spinal cord.

Cerebrospinal fluid (CSF) Clear liquid that fills brain cavities and protects the brain and spinal cord.

Gamma knife High-dose radiation treatment for intracranial tumors.

Intracranial Located within or on the surface of the brain.

Metastatic or secondary brain tumors

Approximately 25% of all cancer patients develop secondary or metastatic brain tumors when cancer cells spread from another part of the body to the brain. Secondary brain tumors are most apt to occur in patients who have:

  • breast cancer.
  • colon cancer.
  • kidney cancer.
  • lung cancer.
  • melanoma (cancer) of the skin. These metastatic brain tumors can develop on any part of the brain or spinal cord.
  • cancer within the nasal passages and/or throat that follow the nerve pathways into the skull, and metastasize to the brain.

Who gets brain tumors

Brain tumors can develop at any age, but are most common in children between the ages of 3-12, and in adults aged 55-65. Primary brain cancer is the second most common cause of cancer death between birth and the age of 34, and the fourth most common cause of cancer death in men aged 35-54. Primary tumors of the brain and central nervous system are often associated with HIV infection. Men and caucasians have a higher risk of developing brain tumors. Other risk factors being studied include children with a history of previous radiation treatment to the head for cancer; parents with certain cancers (nervous system, salivary gland, colon); having an older father; having well-educated parents; occupational exposure to vinyl chloride, lead, and pesticides; history of epilepsy; history of certain genetic conditions (tuberous sclerosis, neurofibromatosis, von Hippel Lindau, familial polyposis, Osler-Weber-Rendu, Li-Fraumeni).

Naming and grading brain tumors

The name of a brain tumor describes where it originates, how it grows, and what kind of cells it contains. A tumor in an adult is also graded or staged according to:

  • how malignant it is
  • how rapidly it is growing and how likely it is to invade other tissues
  • how closely its cells resemble normal cells. (The more abnormal a tumor cell looks, the faster it is likely to grow)

Low-grade brain tumors usually have well-defined borders. Some low-grade brain tumors form or are enclosed (encapsulated) in cysts. Low-grade brain tumors grow slowly, if at all. They may spread throughout the brain, but rarely metastasize to other parts of the body.

Mid-grade and high-grade tumors grow more rapidly than low-grade tumors. Described as "truly malignant," these tumors usually infiltrate healthy tissue. The growth pattern makes it difficult to remove the entire tumor, and these tumors recur more often than low-grade tumors.

A single brain tumor can contain several different types of cells. The tumor's grade is determined by the highest-grade (most malignant) cell detected under a microscope, even if most of the cells in the tumor are less malignant. An infiltrating tumor is a tumor of any grade that grows into surrounding tissue.

Types of brain tumors

Glioma is the term used to refer to the most prevalent primary brain tumors. Gliomas arise from glial tissue, which supports and nourishes cells that send messages from the brain to other parts of the body. These tumors may be either malignant or benign. Astrocytomas, ependymomas, and mixed gliomas are three of the most common gliomas.

ASTROCYTOMAS. Named for the star-like shape of their cells, astrocytomas can develop on any part of the brain or spinal cord. Non-infiltrating astrocytomas grow slowly, and rarely spread to nearby tissue. Mild-to-moderately anaplastic astrocytomas with well-differentiated borders do not grow as slowly as non-infiltrating astrocytomas, and they do spread to surrounding tissues.

Anaplastic astrocytomas, which are also called Grade III astrocytomas, look more abnormal and grow more rapidly than non-infiltrating or mild-to-moderately anaplastic tumors.

Grade IV astrocytomas are also called glioblastoma multiforme (GBM) tumors. Accounting for 30% of all primary brain tumors, GBMs are the most common brain tumors in middle-aged adults. GBMs are the most malignant of all brain tumors. Because they contain a greater mixture of cells than any other brain tumor, they are the most difficult to treat.

EPENDYMOMAS. Also called ependymal tumors, ependymomas account for 9% of all gliomas, and 5% of all intracranial tumors. These tumors, which are most common in children and adolescents, begin in the very thin membranes that help form cerebrospinal fluid (CSF) and line the brain cavities (ventricles) that contain it.

Ependymomas are usually benign, have well-differentiated borders, resemble normal cells, and grow very slowly. The cells of anaplastic (malignant) ependymomas look abnormal and grow more rapidly than the cells of benign tumors.

MIXED GLIOMAS. These heterogeneous tumors contain elements of astrocytomas and ependymomas and/or oligodendrogliomas. These are rare tumors that usually occur in middle-aged adults, grow slowly, and do not usually spread beyond the part of the brain where they originate. Mixed gliomas behave like tumors composed of the highest-grade cells they contain.

Non-glial brain tumors

The most common brain tumors that do not develop from glial cells are medulloblastomas, meningiomas, and Schwannomas.

MEDULLOBLASTOMAS. Scientists once thought medulloblastomas (MDLs) developed from glial cells. These fast-growing, malignant tumors are now believed to originate in developing cells not normally present in the body after birth. They are sometimes called primitive neurodectal tumors (PNET).

MDL tumors are most common in children and are more common in boys than in girls. Only 30% of MDL tumors occur in adults. MDL tumors usually originate in the cerebellum (the part of the brain that controls coordination and some muscle activity), and are often carried to other parts of the brain by cerebrospinal fluid. MDL tumors rarely metastasize beyond the brain and spinal cord.

MENINGIOMAS. Meningiomas, which represent more than 20% of all primary brain tumors, originate in the membranes that enclose the brain and spinal cord (meninges). These tumors are usually benign and most often occur in women aged 30-50 years old. Meningiomas grow so slowly that the brain can sometimes become accustomed to their presence. Meningiomas compress, rather than invade, brain tissue and may grow to be quite large before any symptoms appear.

SCHWANNOMAS. Schwannomas originate in the Schwann cells. These cells produce myelin, material that protects the acoustic nerve, which controls hearing. These benign tumors are twice as common in women as in men, and are most often diagnosed in patients between the ages 30-60.

Schwannomas grow very slowly, and many people adapt to the slight hearing loss and balance problems that are the tumors' earliest symptoms. A pear-shaped Schwannoma can cause sudden or gradual loss of hearing in an ear. As the tumor progresses, it can press on the nerves that control movement and feeling in the face, and cause headaches and facial numbness or tingling. The patient may have trouble walking, swallowing, or controlling eye movements, and the sense of taste can be affected. A Schwannoma that grows large enough to press on the brainstem can be deadly.

CHILDHOOD BRAIN TUMORS. Brain tumors that occur in children are described as supratentorial (in the upper part of the brain) or infratentorial (in the lowest part of the brain). Astrocytomas and ependymomas are common supratentorial tumors. Infratentorial tumors include medulloblastomas, astrocytomas, and ependymomas.

Causes and symptoms

The cause of primary brain tumors is unknown, but people who work with rubber and certain chemicals have a greater-than-average risk of developing them. There is no evidence that head injury causes brain tumors, but researchers are trying to determine the relationship, if any, between brain tumors and viruses, family history, and long-term exposure to electromagnetic fields.

Symptoms do not usually appear until the tumor grows large enough to displace, damage, or destroy delicate brain tissue. When that happens, the patient may experience:

  • headaches that become increasingly painful and are most painful when lying down
  • nausea and vomiting or sudden attacks of vomiting not accompanied by nausea
  • seizures
  • dizziness, loss of coordination or balance
  • personality changes
  • sudden loss of vision
  • memory loss
  • speech problems
  • sensory changes
  • mental impairment
  • weakness or paralysis on one side of the body

A doctor should be notified whenever a patient experiences one or more of the symptoms.

Diagnosis

Although brain tumor symptoms resemble those of many other illnesses, the presence of a brain tumor may be indicated by:

  • persistent headaches with vomiting or convulsions
  • progressive deterioration of sight, speech, hearing, touch; or deterioration in the ability to use an arm, hand, foot, or leg

When a patient experiences one or more of the above symptoms, a primary care physician will perform a complete physical examination, take a detailed medical history, and conduct a basic neurologic examination to evaluate:

  • balance and coordination
  • abstract thinking and memory
  • eye movements
  • hearing, touch, and sense of smell
  • reflexes
  • control of facial muscles and movements of the head and tongue
  • awareness

If the results of these examinations suggest a patient may have a brain tumor, a neurologist recommends some or all of these additional diagnostic tests:

  • computed tomography scan (CT scan) to reveal brain abnormalities
  • magnetic resonance imaging (MRI) to detect tumors beneath the bones of the skull
  • complex imaging techniques such as Positron emission tomography (PET scan), Single photon emission tomography (SPECT scan)
  • electroencephalography (EEG) to measure electrical activity in the brain
  • magnetoencephalography (MEG scan) to measure the magnetic fields produced by nerve cells and their electric currents
  • x rays to reveal any distortion in the bones of the skull
  • angiography to outline a tumor and the blood vessels that lead to it
  • a brain scan to identify and record the location of abnormal cells in the brain
  • radionuclide brain scintigraphy to view the capillaries feeding the tumor after highlighting them with a radioactive substance
  • myelography (x ray of the spine) to detect a spinal cord tumor
  • a lumbar puncture (spinal tap) to obtain spinal fluid, which may contain tumor cells.
  • digital holography to view a complete three-dimensional map of the tumor and surrounding brain structures

Interpreting these images and results of laboratory analysis allows neurologists to determine whether a tumor is present, but microscopic examination of tumor tissue (biopsy) is the only way to identify the kind of cells it contains.

Treatment

Brain tumors are treated by multidisciplinary teams of highly skilled specialists whose decisions are based on:

  • results of diagnostic tests
  • tumor size, position, and growth pattern
  • the patient's health history and current medical status
  • the wishes of the patient and his family

Surgery

Surgery is the treatment of choice for accessible brain tumors, which can be removed without causing serious neurologic damage. The procedure most often performed is a craniotomy, but the goals of any type of brain tumor surgery include:

  • removing as much of the tumor as possible (called debulking the tumor)
  • removing tumor tissue for microscopic analysis
  • allowing neurosurgeons to see exactly how the tumor is situated and how it is growing
  • creating an entry channel for chemotherapy drugs and forms of radiation that are implanted in the brain

Depending on the type of brain tumor, its location, and its size, a number of different techniques may be used to surgically remove it. Surgical techniques include:

  • classic operation
  • laser microsurgery (uses high temperatures to vaporize tumor cells
  • ultrasonic aspiration (uses ultrasound waves to break up the tumor into smaller bits which can be "vacuumed" out

Before undergoing brain surgery, patients are often given:

  • steroids to reduce swelling of brain tissue
  • anticonvulsant medications to prevent or control seizures
  • radiation treatments to reduce tumor size

Patients whose benign brain tumors can be completely removed may not require any additional treatment, but periodic physical and neurologic examinations and CT or MRI scans are sometimes recommended to determine whether the tumor has returned. Because surgeons cannot be sure that every bit of an infiltrating or metastasizing tumor has been removed, radiation and chemotherapy are used to eradicate cells that may have escaped the scalpel.

If a tumor cannot be completely removed, removing a portion of it (debulking) can alleviate the patient's symptoms, enhance the sense of well-being, and increase the effectiveness of other treatments.

Radiation therapy

External radiotherapy, generally delivered on an outpatient basis, directs radiation to the tumor and the area around it. Implant radiation therapy involves placing tiny pieces of radioactive material in the brain. Left in place permanently, or for a short time, these radioactive pellets release measured doses of radiation each day. This technique is called brachytherapy. Patients are usually hospitalized during the several days the pellets are most active.

Stereoactic radiosurgery involves fitting the patient with a frame to stabilize the head, using imaging techniques to determine the exact location of tumor cells, and using a sophisticated instrument to administer radiation precisely to that point. Instruments used for delivery of radiation include the gamma knife, adapted linear accelerator (LINAC), and cyclotron.

A variety of drugs may also be given during radiation therapy, to protect brain cells from the effects of radiation (radioprotective drugs), to increase the sensitivity of tumor cells to radiation (radiosensitizers), or to boost radiation's effects (radioenhancers).

Chemotherapy

One or more cancer-killing drugs may be taken by mouth or injected into a blood vessel, muscle, or the cerebrospinal fluid. Chemotherapy may be used with radiation and surgery as part of a patient's initial treatment, or used alone to treat tumors that recur in the same place or in another part of the body. The usual chemotherapy regimen for a brain tumor is a combination approach, most commonly using procarbazine, CCNU, and vincristine.

New methods of delivering chemotherapy are being used as well. These include:

  • interstitial chemotherapy is performed at the time of surgery. A chemotherapy-soaked wafer is placed in the cavity left after tumor removal.
  • Intrathecal chemotherapy instills the medications right into the spinal fluid.
  • Intraarterial chemotherapy uses tiny catheter tubes to delivery high-dose chemotherapy directly into the arteries of the brain.
  • Potentially toxic chemotherapy drugs can be wrapped in special biologic envelopes called liposomes, to allow the drugs to be delivered to the tumor without adversely affecting other healthy tissues along the way.
  • Electrochemotherapy uses electric voltage to transport chemotherapy agents into the brain.

When a young child has a brain tumor, chemotherapy is often used to eliminate or delay the need for radiation.

Other treatments

If a brain tumor cannot be cured, treatment is designed to make the patient as comfortable as possible and preserve as much of his neurologic functioning as possible. The patient's doctor may prescribe:

  • analgesics to relieve pain
  • anticancer drugs to limit tumor growth
  • anticonvulsants to control seizures
  • steroids to reduce swelling of brain tissue

Potential therapies

Scientists are studying ways to empower chemotherapy drugs to penetrate the blood-brain barrier (which protects the CNS by separating the brain from blood circulating throughout the body), and attack cancer cells that have infiltrated tissue inside it. Agents under investigation include both mannitol and substances called receptor-mediated permeabilizers

Brain tumor researchers are also investigating:

  • Less invasive surgical procedures.
  • Monoclonal antibodies, which pair antibodies with radioactive substances. The antibodies are directed to find and attach to tumor cells, at which time the radioactive substance kills the tumor cell.
  • Interleukin and interferon, which are substances produced naturally by the human immune system which seem to kill tumor cells. Scientists seek to produce these substances in the laboratory and incorporate their use in brain tumor treatment.
  • T-lymphocytes, which are also produced normally by the human immune system, and are being used to inject directly into the tumor location during surgery and to infuse into the bloodstream after surgery, in the hopes that they will boost the immune system's ability to fight tumor cells.
  • Tumor vaccines, which use elements of tumor cells to stimulate the patient's immune system.
  • Methods of incorporating chemotherapy drugs into tumor cells to reduce the need for radiation.
  • Laboratory techniques that enable physicians to select the chemotherapy drugs most likely to kill particular types of tumors.
  • Gene therapy in which genetically engineered material is transported to tumor cells by viruses that infect tumor cells and convert them to normal cells, stop their growth, or kill them.

Alternative treatment

Alternative treatments have not been shown to cure brain tumors and should never be substituted for conventional therapy. However, complementary therapies (used with, not instead of, standard treatments) can help some patients cope with the stress of their illness and side effects of their treatment.

Massage, meditation, and reflexology help some patients relax; while yoga is said to soothe the body, spirit, and mind. Hydrotherapy uses ice, liquid, and steam to improve circulation and relieve pain. Therapeutic touch practitioners say they can relieve pain and other symptoms by moving their hands in slow, rhythmic motions several inches above the patient's body.

Botanical therapies, homeopathic treatment, traditional Chinese medicine treatments, nutritional focuses on diet and supplements, and detoxification can also be incorporated as complementary therapies.

Prognosis

The patient's prognosis depends on where the tumor is located, what type of cells it contains, the size of the tumor, and the effect its already had on adjacent brain structures. A patient whose tumor is discovered early and removed completely may make a full recovery, but the surgery itself can harm or destroy normal brain tissue and cause:

  • problems with thought, speech, and coordination
  • seizures
  • weakness
  • personality changes.

Although these post-operative problems may initially be more severe than the symptoms produced by the tumor, they will probably diminish or disappear in time.

Occupational therapy can teach patients and their families new ways to approach daily tasks. Physical therapy can benefit patients who have difficulty keeping their balance, expressing their thoughts, speaking, or swallowing. Children may need special tutors before and after returning to school. For patients who have incurable brain tumors, hospice care may be available. Hospices provide a supportive environment and help patients manage pain and remain comfortable.

Consequences of radiation therapy

Cells killed by radiation can cluster in the brain, resembling tumors. They can cause headaches, seizures, and memory loss. Children treated with radiation may lose some of their eyesight and develop learning problems. Radiation damage to the pituitary gland can hinder normal growth and development.

Consequences of chemotherapy

Some drugs used to treat brain tumors can cause kidney damage and temporary or permanent tingling in the fingers and ringing in the ears.

Inoperable tumors

Brain tumors that cannot be removed may cause irreversible brain damage and death.

Prevention

The cause of primary brain tumors has not been determined, so there is no known way to prevent them.

The best way to prevent secondary or metastatic brain tumors is to eliminate such risk factors as:

  • poor nutrition and a low-fiber diet; since these contribute to development of intestinal cancers
  • smoking, which causes lung cancer
  • excessive use of alcohol, which is associated with liver cancer
  • excessive exposure to the sun, which can cause melanoma (a deadly form of skin cancer).

Monthly self-examinations of the breasts and testicles can detect breast and testicular cancer at their earliest, most curable stages.

Resources

ORGANIZATIONS

American Brain Tumor Association. 2770 River Road, Des Plaines, IL 60018. (847) 827-9918, (800) 886-2289. http:/www.abta.org.

Brain Tumor Foundation for Children, Inc. 2231 Perimeter Park Drive, Suite 9, Atlanta, GA 30341. (404) 454-5554.

Brain Tumor Information Services. Box 405, Room J341, University of Chicago Hospitals, 5841 S. Maryland Avenue, Chicago, IL 60637. (312) 684-1400.

MedHelp International. 6300 N. Wickham, Suite 130, Box 188, Melbourne, FL 32940. (407) 253-9048. http://www.medhlp.netusa.net.

National Brain Tumor Foundation. 785 Market Street, #1600, San Francisco, CA 94103. http://www.oncolink.penn.edu/psychosocial.

OTHER

Adult Brain Tumor. May 2001. http://cancernet.nci.nih.gov/clinpdq/pif/Adult_brain_tumor_Patient.html.

Brain Tumor, Primary. Nidus Information Services, Well Connected, 2001.

"Brain Tumors," Abeloff: Clinical Oncology, 2nd ed. Churchill Livingstone, Inc., 2000.

"Brain Tumors," Goldman: Cecil Textbook of Medicine. 21st ed. W. B. Saunders Company, 2000.

Childhood Brain Tumor. May 2001. http://cancernet.nci.nih.gov/clinpdq/pif/Childhood_brain_tumor_Patient.html.

Question: What is a Gamma Knife? April 13, 2001. http://oncolink.upenn.edu/specialty/med_phys/gamma.html.

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Brain Tumor

Brain Tumor

What is a Brain Tumor?

Why Do People Develop Brain Tumors?

What are the Symptoms of a Brain Tumor?

How Do Doctors Diagnose Brain Tumors?

How Do Doctors Treat Brain Tumors?

Life After a Brain Tumor

Resources

A brain tumor is a mass of abnormal cells growing in the brain. Despite its frightening name, not all brain tumors are cancerous or fatal.

KEYWORDS

for searching the Internet and other reference sources

Astrocytoma

Ependymoma

Germinoma

Glioma

Medulloblastoma

Meningioma

Neuroblastoma

Oncology

What is a Brain Tumor?

A brain tumor is a clump of abnormal tissue that can be found anywhere in the brain. The brain and spinal cord form the central nervous system, which controls everything a person does on purpose (such as walking and talking), or automatically (such as breathing and digesting food). This system also controls people s senses, emotions, thoughts, memory, and personality; it determines who they are.

Brain tumors are categorized in two ways: first, by how they look during imaging tests that create pictures of the brain, and by how the tissue appears under a microscope; and second, according to whether they started in the brain or spread there from another part of the body.

  • Benign brain tumors have clearly defined edges and contain cells that look healthy, just like normal cells. They tend to grow slowly, are not likely to spread, and rarely grow back once they are removed. The word benign means harmless, although these tumors may cause harm if they start to interfere with normal brain function. Benign brain tumors are not cancerous.
  • Malignant brain tumors are also called brain cancer. They can have irregular borders and they are made up of abnormally shaped cells. They tend to spread quickly by sprouting new roots into surrounding brain tissue, almost like a plant in the soil. While they may also spread to the spinal cord, they generally do not spread to other parts of the body. In some cases, one tumor may contain a combination of nearly normal and extremely abnormal cells.
  • Primary brain tumors originate in the tissues of the brain and may be either benign or malignant.
  • Secondary brain tumors are actually formed from cancer cells that have traveled to the brain from another part of the body. For example, cells from tumors in the lung, breast, or somewhere else can spread to the brain and cause new tumors to grow. Secondary brain tumors are always malignant.

In addition, brain tumors are classified by the type of brain cell that became a tumor, with medical names such as astrocytoma (as-tro-sy-TO-ma), glioma (glee-O-ma), ependymoma (e-pen-di-MO-ma), germinoma (jer-mi-NO-ma), medulloblastoma (med-yoo-lo-blas-TO-ma), meningioma (me-nin-jee-O-ma), and neuroblastoma (noor-o-blas-TO-ma). Their common ending -oma means tumor, and the beginning indicates the part of the brain where the tumor forms. For example, gliomas, the most common type of brain tumor, form in the supportive tissue of the brain, called the glia. The second most common type, meningioma, forms in the meninges, the membranes that cover the brain and spinal cord.

Why Do People Develop Brain Tumors?

Doctors cannot explain why some children and adults develop brain tumors. When it happens, it is not their fault, nor could they have done anything to prevent it. Even though a tumor can spread within the brain, it cannot spread from one person to another; in other words, brain tumors are not contagious.

Researchers have found that some brain tumors are more common in people who are frequently exposed to certain industrial chemicals used to manufacture rubber, pharmaceuticals, crude oil and petroleum, and nuclear fuel and weapons, as well as agricultural chemicals used on farms. They also are investigating whether certain viruses may contribute to brain tumor development.

Heredity is another possible cause under investigation. Because brain tumors sometimes occur in several members of the same family, researchers are investigating whether the tendency to develop them may be inherited.

What are the Symptoms of a Brain Tumor?

As the tumor grows, it exerts pressure on the brain that often causes headaches, drowsiness, blurred or double vision, or nausea and vomiting. Of course, most times these symptoms are not caused by brain tumors. Because different parts of the brain control specific functions in the body, a tumors symptoms often depend on its location in the brain. Symptoms may include:

  • Seizures, or sudden movements or changes in consciousness over which the person has no control.
  • Weakness or loss of feeling in the arms or legs.

50 Years Ago: Johnny Gunther

Brain tumors affect people of all ages. Among children and young adults who have tumors, it is one of the more common types diagnosed. Still, childhood brain tumors are relatively rare: the American Brain Tumor Association estimates that only about 4 of every 100,000 children under age 20 will develop a brain tumor.

Back in 1946, one such child was Johnny Gunther, whose father wrote the widely read book Death Be Not Proud about Johnnys experiences. At the age of 16, Johnny started experiencing some vision problems and a stiff neck. After a series of tests, he was diagnosed with glioblastoma, a fast-growing tumor that tends to spread quickly within the brain.

The book describes the diagnostic tests that Johnny underwent and his treatments, including surgery and radiation therapy, which was called x-ray therapy at that time. Johnnys father also recounts how the family coped with the disease and the eventual knowledge that Johnny would not get better. Johnny died in 1947 at the age of 17.

Johnnys tumor is not typical of all brain tumors. Some grow much more slowly and do not invade the surrounding tissue. Gunther notes that while his sons tumor looked like a spider stretching out its legs, another type might look more like a marble stuck in jelly.

Treatment methods for all types of brain tumors have advanced since 1946, making it easier for doctors to remove them and control their growth. Johnnys doctors had to rely on x-rays, vision tests, and a brain wave test called an electroencephalogram to locate his tumor. Now, doctors use CTs, MRIs, and other new computer technologies to create visual maps of the brain and pinpoint a tumors exact location before and during surgery.

  • Stumbling or lack of coordination in walking.
  • Abnormal eye movements or changes in vision.
  • Changes in personality or memory.
  • Speech problems.

How Do Doctors Diagnose Brain Tumors?

In addition to asking about symptoms, the doctor performs a neurological exam, which involves different tests of vision and eye movement, hearing, reflexes, balance and coordination, memory, thinking ability, and other functions controlled by the brain.

The doctor is also likely to order imaging tests such as a computerized tomography (CT) scan (a special x-ray that uses a computer to create pictures of the brain), or a magnetic resonance imaging (MRI) scan, which creates a picture of the brain by using a very strong magnetic field instead of x-rays. Another possible type of test, called angiogram imaging,

involves injecting dye into a blood vessel and creating a series of images as the dye moves through the brain. This helps doctors to visualize the tumor and the blood vessels leading to it.

Once a tumor is found, doctors often need to gather more information to figure out what type it is. In some cases, the doctor takes a sample of the cerebrospinal fluid that surrounds the brain and spinal cord, and then sends the fluid to be examined under a microscope. More commonly, surgeons will remove part or all of the tumor in a process called a biopsy, and then send the tissue to the laboratory for analysis. To get at the tumor, they open part of the skull (a procedure called craniotomy), or they may drill a small hole in the skull and use a needle to take a tissue sample. Both before and sometimes during the operation, surgeons use computerized images of the brain to help them locate the tumor and avoid the nearby healthy tissues that are essential for normal function.

Dr. Harvey Cushing

Surgeons performed the first successful removals of brain tumors during the 1880s. Follow-up care was difficult, however, and many patients died afterward.

During the early years of the twentieth century, Dr. Harvey Cushing (1869-1939) pioneered the specialty of neurosurgery in the United States. Dr. Cushing made certain that all types of tumors were classified before surgery based on analysis of the tumor s pattern of growth and on observation of tissue samples. His work also revolutionized post-operative care, which reduced mortality among tumor patients. Dr. Cushings achievements are reflected in todays surgical techniques, clinical expertise, and laboratory research.

How Do Doctors Treat Brain Tumors?

Surgery, radiation therapy, and chemotherapy are the three most common treatments for a brain tumor. But the type of tumor, its location, and the persons age often determine how these treatments are used. Before the process starts, most patients are given medications to relieve any swelling in the brain and control the seizures that often occur with brain tumors.

Stereotactic Surgery

Stereotactic surgery uses a frame attached externally to the skull. The frame allows the surgeon to attach surgical instruments and to position them precisely.

Before surgery, tumor locations are identified using computerized tomography (CT) or magnetic resonance imaging (MRI). The surgeon then drills a small hole in the skull and, using the CT or MRI data, inserts the instruments and navigates to an exact point in the brain. The surgeon can then remove a tumor or perform other procedures.

Doctors often use stereotactic surgery to guide biopsy needles and forceps, to guide electrodes for recording or marking lesions, to guide lasers, to insert endoscopes for looking inside the body, and to guide Gamma knife procedures, which use radiation to do surgery.

Surgery

During surgery, surgeons attempt to remove the entire tumor. However, if the tumor cannot be removed completely without damaging vital brain tissue, then they will remove as much as they can. Surgery is usually the only treatment needed for a benign tumor.

Radiation therapy

Radiation therapy (also called radiotherapy) is the use of high-powered radiation to destroy cancer cells or stop them from growing. It is often used to destroy tumor tissue that cannot be removed with surgery, or to kill cancer cells that may remain after surgery. Radiation therapy is also used when surgery is not possible. External radiation comes from a large machine, while internal radiation involves implanting radioactive material directly into the tumor. Even though the radiation is focused on the tumor, some of the surrounding healthy tissue is often damaged as well. Therefore, doctors avoid giving radiation to very young children, especially those under age 3, because their brains are still developing. These children are often treated with chemotherapy until they are old enough to have the radiation therapy.

Chemotherapy

During chemotherapy, doctors give anticancer drugs by mouth or by injection into a blood vessel or muscle. Because the body automatically tends to prevent chemicals and other foreign substances from entering the brain and spinal cord (a kind of self-defense mechanism), doctors may need to inject them right into the spinal fluid.

New treatments

Numerous other treatments for brain tumors are being evaluated in research studies called clinical trials. For example, researchers are testing biological therapies that try to supercharge the bodys disease-fighting immune system against the tumor. They also are testing drugs that would prevent tumors from creating the new blood vessels they need to keep growing. In the United States, the National Cancer Institute has formed groups of doctors nationwide who are working together to find new treatments for brain tumors in children and adults.

Life After a Brain Tumor

Sometimes, the tumor or the treatment damages some of the nearby healthy brain tissue that controls physical and mental function. Patients need to work with a special therapist if they are having trouble using their arms or legs, maintaining balance, speaking, swallowing, or expressing their thoughts. They may feel tired or depressed, and they may experience personality changes. Children may find that they have problems with learning or remembering what they learn when they return to school.

See also

Cancer

Resources

Books

Gunther, John. Death Be Not Proud: A Memoir. New York: HarperPerennial Library, 1998. First published in 1949.

Roloff, Tricia Ann. Navigating Through a Strange Land: A Book for Brain Tumor Patients and Their Families. Indigo Press, 1995.

Organizations

U.S. National Cancer Institute (NCI). One of the National Institutes of Health, NCI publishes brochures about cancer, including the fact sheet What You Need to Know About Brain Tumors. Telephone 800-4-CANCER http://cancernet.nci.nih.gov/wyntk_pubs/index.html

American Brain Tumor Association, 2720 River Road, Des Plaines, IL 60018. The ABTA offers free publications about brain tumors, including A Primer of Brain Tumors: A Patients Reference Manual, Alexs Journey: The Story of a Child with a Brain Tumor (especially for children ages 9 to 13), Dictionary for Brain Tumor Patients, and many others. Telephone 800-886-2282 http://www.abta.org

National Brain Tumor Foundation, 785 Market Street, Suite 1600, San Francisco, CA 94103. NBTF publishes Brain Tumors: A Guide and its website features descriptions of different brain tumor types, survivors stories, and a physician interview. Telephone 800-934-CURE http://www.nbtf.org.

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Brain Tumor

Brain Tumor

Definition

A brain tumor is an abnormal growth of tissue, either malignant (cancerous) or benign (noncancerous), in the brain. Each year, more than 17,000 brain tumors are diagnosed in the United States.

Description

Benign brain tumors

A benign brain tumor is composed of slow-growing noncancerous cells that never spread (by local extension or any other means) beyond the site where they originate. Common benign tumors are meningiomas, acoustic neuromas, pituitary gland tumors, craniopharyngiomas, germinomas, pinealomas, and hemangioblastomas. Even though a tumor is benign, it may still be dangerous because, depending on its location, it may be inoperable and/or affect one or more brain functions.

Benign brain tumors have clearly defined borders, can often be removed completely, especially if they are on the brain's surface, and are unlikely to recur. Benign brain tumors do not infiltrate nearby tissues but as they continue to grow can cause severe pain, permanent brain damage, and death. Benign brain tumors sometimes become malignant.

Malignant brain tumors

A brain tumor is considered malignant if it contains cancer cells. Unlike other tumors, these spread by local extension and rarely metastasize beyond the brain. About half of all brain tumors are malignant.

Malignant brain tumors do not have distinct borders. They tend to grow rapidly, increase intracranial pressure, and metastasize to other parts of the brain or spinal cord. It is highly unusual for malignant brain tumors to spread beyond the central nervous system (CNS).

Primary brain tumors

Primary brain tumors originate in the brain. They represent about 1% of all cancers and 2.5% of all cancer deaths.

Metastatic or secondary brain tumors

Most brain tumors do not originate in the brain; they are metastases from other primary cancer sites. Approximately 25% of all cancer patients develop secondary or metastatic brain tumors when cancer cells spread from another part of the body.

Secondary brain tumors are most apt to occur in patients who have melanoma, breast, colon, kidney, or lung cancer. Brain metastases can develop on any part of the brain or spinal cord.

Patient demographics

Primary brain tumors may develop at any age, but are most common in children between the ages of three and 12, and in adults aged 40-70. Primary brain cancer is the second-most common cause of cancer death between birth and the age of 34, and the third-most common cause of cancer death in men aged 35-54. Primary tumors of the brain and central nervous system are associated with AIDS in some patients.

Naming and grading brain tumors

A brain tumor's name describes its origin, how it grows, and the cell type it contains. A tumor in an adult is also graded or staged according to the extent or degree to which it is malignant; how rapidly it is growing, and how likely it is to invade other tissues; and how closely its cells resemble normal cells. (The less normal a tumor cell appears, the faster it is likely to grow.)

Low-grade tumors usually have well-defined borders. Some low-grade brain tumors form or are encapsulated (enclosed) in cysts. Low-grade brain tumors grow slowly, if at all. They may spread throughout the brain, but rarely metastasize to other parts of the body.

Mid- and high-grade tumors grow more rapidly than low-grade tumors; these tumors usually infiltrate healthy tissue. Their growth pattern makes it difficult to remove the entire tumor, and they recur more often than low-grade tumors.

A single brain tumor can contain several different types of cells. The tumor's grade is determined by the highest-grade (most malignant) cell detected under a microscope, even if most of the cells in the tumor are less malignant. An infiltrating tumor is a tumor of any grade that grows into surrounding tissue.

Types of brain tumors

Glioblastomas, also known as gliomas, are the most prevalent primary brain tumors. They arise from glial tissue, which supports and nourishes cells that send messages from the brain to other parts of the body. Gliomas can be either malignant or benign. Astrocytomas, ependymomas, and mixed glioblastomas are three of the most common types.

ASTROCYTOMAS. Named for their star-shaped cells and the tumor's radiating tentacles, astrocytomas can develop on any part of the brain or spinal cord. Noninfiltrating astrocytomas grow slowly, and rarely spread to nearby tissue. Mild-to-moderately anaplastic (malignant) astrocytomas with well-differentiated borders grow more quickly, and tend to infiltrate surrounding tissues. These are grade I and II astrocytomas.

Anaplastic, or grade III astrocytomas, look more abnormal and grow more rapidly than noninfiltrating or mild-to-moderately anaplastic tumors. Grade IV astrocytomas are also called glioblastoma multiforme (GBM) tumors. Accounting for 30% of all primary brain tumors, GBMs are the most common brain tumors in middle-aged adults. GBMs are also the most malignant of all brain tumors. Because they contain a greater mixture of cells than any other brain tumor, they are the most difficult to treat.

EPENDYMOMAS. Also called ependymal tumors, ependymomas account for 9% of all gliomas, 5% of all intracranial tumors, and are the most common brain tumors in children and adolescents. They begin in the ependymal cells that line the central canal of the spinal cord and the ventricles of the brain, where cerebrospinal fluid (CSF) is manufactured.

Ependymomas are often benign, have well-differentiated borders, resemble normal cells, and grow very slowly. The cells of anaplastic ependymomas look abnormal and grow more rapidly than the cells of benign tumors.

MIXED GLIOMAS. These heterogeneous tumors contain elements of astrocytomas, ependymomas, and/or oligodendrogliomas. These rare tumors usually occur in middle-aged adults, grow slowly, and do not usually spread beyond the part of the brain where they originate. Mixed gliomas follow the patterns of growth related to the highest-grade cells they contain.

Nonglial brain tumors

MEDULLOBLASTOMAS. Scientists once thought medulloblastomas (MDLs) developed from glial cells. These fast-growing malignant tumors are now believed to originate in embryonal cells not normally present in the body after birth. They are sometimes called primitive neurodectal tumors (PNET).

MDL tumors are most common in children and are found more often in males than females; only 30% occur in adults. MDL tumors usually originate in the cerebellum and often metastasize to other parts of the brain via cerebrospinal fluid. They rarely metastasize beyond the brain and spinal cord.

MENINGIOMAS. Meningiomas, which represent more than 20% of all primary brain tumors, originate in the meninges (the membranes that cover the brain and spinal cord). These tumors are usually benign and most often occur in women aged 30-50 years old. Meningiomas grow so slowly that the brain can sometimes become accustomed to their presence. Meningiomas compress brain tissue rather than invade it, and may grow to be quite large before any symptoms appear.

ACOUSTIC NEUROMA. These benign tumors, also known as vestibular schwannomas, are named for the cells in which they orginate. In this case, the tumor is named for the Schwann cells, which produce myelin, the material that sheaths all nerves. Acoustic neuromas are usually found on the auditory nerve, which controls hearing. They are twice as common in women as in men, and are most often diagnosed in patients between the ages 30-60.

Acoustic neuromas grow very slowly, and many patients adapt to the hearing loss balance problems, and tinnitus that are the tumors' earliest symptoms. As the tumor progresses, it can press on the nerves that control movement and sensation in the face, and cause headaches and facial numbness or tingling. The patient may have trouble walking, swallowing, or controlling eye movements, and the sense of taste can be affected. An acoustic neuroma that grows large enough to press on the brainstem can be deadly.

CHILDHOOD BRAIN TUMORS. Brain tumors that occur in children are treated differently than those found in adults because they usually appear in different parts of the brain, cause different symptoms, and require different treatment because of the patient's age and stage of development. They also often have a better prognosis than adult tumors.

Brain tumors are rare in children—only about 2,200 are diagnosed in the United States each year. Children under seven are most likely to be afflicted, with boys affected more often than girls. Headaches, nausea, vomiting, difficulty walking, vision problems, and changes in schoolwork are the chief symptoms.

Unlike adult tumors, childhood brain tumors are identified primarily by their location, either supratentorial (above the tentorium, the membrane that separates the brain from the cerebellum) or infratentorial (below the tentorium). Astrocytomas and ependymomas are common supratentorial tumors. Infratentorial tumors include medulloblastomas, astrocytomas, and ependymomas.

Causes and symptoms

The causes of primary brain tumors are unknown, but people who work with vinyl chlorides, polycyclic hydrocarbons, nitrosoureas, and certain pesticides have a greater-than-average risk of developing them. There is no evidence that head injury causes brain tumors, but researchers are trying to determine the relationship, if any, between brain tumors and viruses, genetic susceptibilities, and long-term exposure to electromagnetic fields.

Although brain tumor symptoms resemble those of many other illnesses, the presence of a brain tumor may be suspected in patients who have persistent headaches with vomiting or convulsions; progressive deterioration of sight, speech, hearing, touch; or deterioration in the ability to use an arm, hand, foot, or leg. Symptoms often do not appear until the tumor grows large enough to displace, damage, or destroy delicate brain tissue.

Diagnosis

When a patient experiences one or more of the above symptoms, a primary care physician will perform a focused physical examination, take a detailed medical history, and conduct a basic neurologic examination to evaluate:

  • balance and coordination
  • abstract thinking and memory
  • eye movements
  • hearing, touch, and sense of smell
  • reflexes
  • control of facial muscles and movements of the head and tongue
  • awareness

If the results of these examinations suggest a patient may have a brain tumor, the patient is referred to a neurologist or neurosurgeon, who will recommend any or all of several diagnostic tests:

  • a computed tomography scan (CT scan) to reveal brain abnormalities
  • magnetic resonance imaging (MRI) to detect tumors beneath the bones of the skull
  • electroencephalography (EEG) to measure the electrical activity in the brain when seizures are suspected
  • angiography can outline a tumor and the blood vessels that lead to it
  • a lumbar puncture (spinal tap) to see if spinal column pressure has increased and if the spinal fluid contains tumor cells

Interpreting these images and results enables the physicians to determine whether a tumor is present, but biopsy (microscopic examination of tumor tissue) is the only way to identify its cell type.

Treatment

Patients with brain tumors are treated by multidisciplinary teams of highly skilled specialists whose decisions are based on test results; tumor size, position, and growth pattern; the patient's history and current medical status; and the patient's wishes.

Surgery

Surgery is the treatment of choice for accessible brain tumors that can be removed without causing serious neurological damage. A craniotomy, the procedure performed most often, allow surgeons to remove as much of the tumor as possible and send a specimen to the laboratory for microscopic analysis. The operation also creates an entry channel for chemotherapy drugs and forms of radiation that are implanted in the brain.

Prior to surgery, patients are often given corticosteroids and other medications to reduce swelling of brain tissue and anticonvulsants to prevent or control seizures. Preoperative radiation treatments may also be administered to reduce tumor size.

Patients whose benign brain tumors can be completely removed may not require any additional postoperative treatment, however, periodic physical and neurologic examinations and CT or MRI scans are usually recommended to determine whether the tumor has returned. Surgeons cannot be absolutely sure that every bit of an infiltrating or metastasizing tumor has been removed and microscopic growth may still exist, so radiation and chemotherapy are used to eradicate malignant cells that may have escaped the scalpel.

If a tumor cannot be completely removed, debulking (removing a major portion of it) can alleviate symptoms, enhance the sense of well-being, and increase the effectiveness of other treatments.

Radiation therapy

External radiotherapy is generally delivered on an outpatient basis, and directs radiation to the tumor and the area around it. Implant radiation therapy involves placing radioactive material into channels made in the brain. Left in place permanently, or for a short time, these radioactive pellets, sometimes called seeds, release measured doses of radiation each day. Patients are usually hospitalized for observation during the several days the pellets are most active. Immediate family are encouraged to keep a distance or use protective gear, in some instances, during this period.

Stereoactic radiosurgery involves fitting the patient with a frame to stabilize the head, using imaging techniques to determine the exact location of tumor cells, and using a sophisticated instrument called a gamma knife to administer radiation precisely to that point.

Chemotherapy

One or more anticancer drugs may be taken by mouth or injected into a blood vessel, muscle, or the cerebrospinal fluid to kill malignant cells. Chemotherapy may be used in combination with radiation and surgery as part of initial treatment, or used alone to treat tumors that recur in the same place or in another part of the body. When a young child has a brain tumor, chemotherapy is often used to eliminate or delay the need for radiation.

Other treatments

If a brain tumor cannot be eradicated, treatment is designed to make the patient as comfortable as possible and preserve as much neurologic function as possible. The patient's physician may prescribe analgesics to relieve pain, anticancer drugs to limit tumor growth, anticonvulsants to control seizures, and steroids to reduce swelling of brain tissue.

Potential therapies

Researchers are exploring ways to empower chemotherapy drugs to penetrate the blood-brain barrier (which protects the CNS by separating the brain from blood circulating throughout the body), and attack cancer cells that have infiltrated tissue inside it. The goal is to target these drugs to certain types of cells or cell-growth mediators, keeping healthy brain tissue unaffected.

Researchers also are investigating:

  • less-invasive surgical procedures
  • methods of incorporating chemotherapy drugs into tumor cells to reduce the need for radiation
  • laboratory techniques that enable physicians to select the chemotherapy drugs most likely to kill particular types of tumors
  • gene therapy in which genetically engineered material is transported to tumor cells by viruses that infect tumor cells and convert them to normal cells, stop their growth, or kill them

Alternative therapies have not been demonstrated to cure brain tumors and should never be substituted for conventional therapy. However, complementary therapies (used with, not instead of, standard treatments) may help some patients cope with the stress of illness and side effects of their treatment. Among these are biofeedback training, massage, meditation, and botanical and homeopathic treatments.

Biofeedback can teach patients to influence and control heart rate, muscle tension, and other stressrelated body functions. Some patients claim that guided imagery (visualization) helps them feel healthier and more in control of their disease.

Massage, meditation, guided imagery, and reflexology help some patients relax; while yoga is said to soothe the body, spirit, and mind while reducing the other effects of stress. Hydrotherapy uses ice, liquid, and steam to improve circulation and relieve pain. Body work and therapeutic touch may help relieve pain and other symptoms.

Some patients and practitioners incorporate botanical therapies, homeopathic treatment, traditional Chinese medicine treatments, changes in diet, and use of dietary supplements as complementary therapies.

Health care team roles

Brain tumor diagnosis and treatment involves a multidisciplinary team of health care professionals. In addition to primary care physicians, such as a family practitioner or an internist, the treatment team may include a neurologist, neurosurgeon, pathologist, radiologist, as well as clinical specialists and advanced practice nurses, physical and occupational therapists, radiologic and laboratory technicians, and dietitians and nutritionists. Social workers and case managers help with arrangements for home-care treatment or interim facility care.

Patient education

Before, during and after treatment, nurses and allied health professionals should inform and educate patients and families about the risks and complications of any planned diagnostic test, intervention or treatment. It is important to realize that in order for informed consent to be valid, the surgeon or other physician must be the one to offer initial information on the pros and cons of therapies. Patients and families should be taught about some of the common side effects of treatment including weight loss, malnutrition, increased risk of infection, pain, fatigue, and depression.

Occupational therapists can teach patients and families new ways to approach daily tasks. Physical therapists, physical therapy assistants, and speech therapists can help patients who have difficulty keeping their balance, expressing their thoughts, speaking, or swallowing. Children may need special tutors and counseling before and after returning to school. For patients who have incurable brain tumors, hospice care can provide a supportive environment and specially trained health professionals to help patients manage pain and remain comfortable, whether at home or in a treatment facility.

Prognosis

The patient's prognosis depends on the location of the tumor and its cell type. A patient whose tumor is discovered early and removed completely may make a full recovery, but the surgery itself may harm or destroy normal brain tissue. This can result in additional problems, such as seizures, weakness, personality changes, or thought, speech, and coordination difficulties. Although these postoperative problems may initially be more severe than the symptoms produced by the tumor, they usually diminish or disappear over time.

Consequences of radiation therapy

Cells killed by radiation can cluster in the brain, resembling tumors. These dead-cell clusters can cause headaches, seizures, and memory loss. Children treated with radiation may lose some of their eyesight and develop learning problems. Radiation damage to the pituitary gland can hinder normal growth and development.

Consequences of chemotherapy

Some anticancer drugs may cause kidney damage and other temporary or permanent dysfunction, such as tingling in the fingers and ringing in the ears.

Inoperable tumors

Brain tumors that cannot be removed may cause irreversible brain damage and death.

Prevention

Since the causes of primary brain tumors have not been determined conclusively, there is no known way to prevent them. The best way to prevent secondary or metastatic brain tumors is to reduce risk factors such as:

  • poor nutrition and a low-fiber diet; since these contribute to development of intestinal cancers
  • smoking, which can cause lung cancer
  • excessive alcohol consumption, which is associated with liver cancer
  • excessive exposure to the sun, which can cause melanoma

KEY TERMS

Central nervous system (CNS)— The division of the nervous system that consists of the brain and spinal cord.

Cerebrospinal fluid (CSF)— Clear lymph-like liquid that fills brain cavities and protects the brain and spinal cord.

Craniotomy— Surgical procedure in which part of the skull is removed (then replaced) to allow access to the brain.

Gamma knife— High-dose radiation treatment for intracranial tumors.

Intracranial— Located within or on the surface of the brain; within the cranium (skull).

Malignant— A cancerous or life-threatening tumor.

Melanoma— A particularly deadly type of skin cancer that develops in the melanocytes, or skin-pigmenting cells.

Metastasis— Spread of disease, particularly cancer, from one part of the body to another.

Resources

BOOKS

Cicala, Roger S. The Brain Disorders Sourcebook. Lowell House, 1999.

Kleihues, P., and Webster K. Cavanee, eds. "Pathology and Genetics of Tumours of the Nervous System." In World Health Organization Classification of Tumours, 2nd edition. Oxford University Press, 2000.

Murphy, Gerald P., et al. American Cancer Society Textbook of Clinical Oncology, 2nd edition. Atlanta, GA: The American Cancer Society, Inc., 1995.

PERIODICALS

Moulignier, Antoine, et al. "Cerebral Glial Tumors and Human Immunodeficiency Virus-1 Infection: More Than a Coincidental Association." Cancer 74, no. 2 (July 15, 1994): 686-87.

ORGANIZATIONS

American Brain Tumor Association. 2770 River Road, Des Plaines, IL 60018. (847) 827-9918. 〈http://www.abta.org〉.

Brain Tumor Foundation for Children, Inc. 2231 Perimeter Park Drive, Suite 9, Atlanta, GA 30341. (404) 454-5554.

Brain Tumor Information Services. Box 405, Room J341, University of Chicago Hospitals, 5841 S. Maryland Avenue, Chicago, IL 60637. (312) 684-1400.

MedHelp International. 6300 N. Wickham, Suite 130, Box 188, Melbourne, FL 32940. (407) 253-9048. 〈http://www.medhlp.netusa.net〉.

National Brain Tumor Foundation. 785 Market Street, #1600, San Francisco, CA 94103. 〈http://www.oncolink.penn.edu/psychosocial.〉.

OTHER

"Adult Brain Tumor." National Cancer Institute. CancerNet. 〈http://cancernet.nci.nih.gov/clinpdq/pif/Adult_brain_tumor_Patient.html〉(June 28, 2001).

"Brain Tumors." National Cancer Institute. CancerNet. 〈http://rex.nci.nih.gov/WTNK_PUBS/brain/index.htm〉 (June 28, 2001).

Bourland, J. Daniel. "Question: What is a Gamma Knife?" 〈http://oncolink.upenn.edu/specialty/med_phys/gamma.html〉 (June 28, 2001).

Kelly, Patrick J. "Brain Tumors: Their Symptoms, Therapy, and Future Cure." New York University, Department of Neurosurgery. 〈http://mcns10.med.nyu.edu/intro/treatment.html〉 (June 28, 2001).

Packer, Roger, Colleen Snyder, and Elizabeth Irvin. "Brain Tumors in Children." American Brain Tumor Association. 〈http://www.abta.org/primer/childhood.htm〉.

American Brain Tumor Association. "A Primer of Brain Tumors: A Patient's Reference Manual." 〈http://neurosurgery.mgh.harvard.edu/abta/primer.htm〉 (June 28, 2001).

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