Brain Tumor Overview

A brain tumor is an abnormal mass or lump caused by cells growing out of control in the brain. Brain tumors are not as common as other types of tumors. They can be dangerous, however, because of their location in the brain and because they can sometimes grow aggressively and spread to other areas of the brain. Symptoms of brain tumors vary according to the area of the brain in which they occur.

While there are many types of brain tumors, they are typically placed into two basic categories-primary and secondary brain tumors:

Primary Brain Tumors

Primary brain tumors are those that start in the brain. They can be either benign (composed of slow-growing cells that usually do not spread) or malignant (made up of fast-growing cancerous cells that spread into surrounding tissue). The term malignant, however, is also applied to a benign brain tumor that behaves aggressively or is life-threatening due to its location in relation to sensitive areas of the brain. Approximately 8.2 out of every 100,000 people are diagnosed with primary malignant brain tumors each year.

Tumors are also classified into grades that indicate how they look under a microscope and how rapidly they are expected to grow. A low-grade tumor, for example, is expected to grow at a slow to moderate rate, while a high-grade tumor is expected to grow rapidly.

Brain tumors are named for the cell types from which they originate. Primary brain tumors fall into two categories-gliomas and non-gliomas:

Gliomas are tumors that grow from glial cells, commonly called neuroglia or simply glia. Glial tissue supports and nourishes the brain. Nearly 50 percent of all primary brain tumors are benign or malignant gliomas. They usually grow in the cerebral hemispheres, but can also occur in the optic nerve, the brain stem, and, often in children, the cerebellum. Many gliomas infiltrate critical brain tissue, making them difficult or impossible to remove surgically. There are several types of gliomas:

• Astrocytomas are the most common type of glioma. Grades I and II account for 25 percent to 30 percent of all gliomas. They originate in star-shaped cells called astrocytes anywhere in the central nervous system. Low-grade, or slow-growing astrocytomas may be completely removed by surgery; whereas, high-grade or faster growing tumors are customarily treated with surgery, radiation and chemotherapy, combined.
• Glioblastomas multiforme are another name for high-grade malignant astrocytomas whose extremely aggressive cells rapidly invade nearby tissues. They contain areas of dead tumor cells and are among the most common primary brain tumors that affect adults. Men are more frequently diagnosed with glioblastomas than women, but they can also affect children. About half of all astrocytomas are glioblastomas. They are typically treated with surgery followed by radiation alone or in combination with chemotherapy.
• Brain stem gliomas occur in the brain stem. They are comprise about 20 percent of all childhood tumors, frequently occurring between the ages of three and 10-and about 5 percent of adult tumors. They range from very low-grade astrocytomas to more rapidly growing glioblastomas. Surgery is not usually an option because the brain stem is so easily damaged. Radiation therapy is one alternative, helping to reduce symptoms and improving survival by slowing tumor growth. All brain stem gliomas are dangerous but if they are low-grade, they can exhibit extended periods of remission after treatment
• Oligodendrogliomas are slow-growing, sharply defined tumors. Relatively rare, they account for about 3 percent of primary brain tumors and most are found in the cerebral hemispheres of young adults. In 50 percent of patients, seizures are usually the first symptom of an oligodendroglioma. Surgery is usually the first treatment for these tumors, but surgery on high-grade tumors is followed with radiation therapy. Sometimes chemotherapy is added, because these tumors are only moderately sensitive to radiation. Oligodendrogliomas may be malignant.
• Ependymomas are mostly low-grade tumors that may be either benign or malignant, based upon their type and location. They make up about 5 percent of adult intracranial gliomas and as much as 10 percent of childhood central nervous system tumors. About 85 percent are non-cancerous. Radiation therapy is the usual treatment, although some ependymomas must be entirely removed by surgery.

Non-gliomas are usually benign tumors such as meningiomas and pituitary adenomas, as well as malignant tumors such as primitive neuroectodermal tumors (medulloblastomas), primary central nervous system (CNS) lymphomas, and CNS germ cell tumors (rare). Non-glioma brain tumors include:

• Medulloblastomas, also called neuroectodermal tumors, are highly malignant primary brain tumors originating in the cerebellum or posterior fossa and spreading through the cerebrospinal fluid to the spine and other parts of the body. They are more frequently found in children, accounting for more than a quarter of all childhood brain tumors. Increased pressure in the brain causes listlessness, vomiting and morning headaches. Surgery and radiation alone are the usual treatments, but these tumors are very sensitive to radiation and chemotherapy, as well.
• Meningiomas are benign tumors that develop in the thin membranes, or meninges, covering the brain and spinal cord. Symptoms depend on location, but they usually grow slowly and don't ordinarily invade surrounding tissue or spread to other parts of the central nervous system or body. They represent about 27 percent of all primary brain tumors and tend to affect more women than men. Some meningiomas grow more rapidly or have sudden growth spurts. Since they compress adjacent brain tissue, they can be life threatening. They are unpredictable and can recur, making follow-up scans important. Surgery, particularly for medium to large meningiomas, is more successful than for most other brain tumor types and is the preferred treatment for accessible meningiomas.
• Schwannomas are usually benign tumors that may grow on one or both sides of the brain. Since they are a tumor of the tissue (Schwann cells) covering nerves, they can occur anywhere in the body. When possible, they are surgically removed. One common form, known as vestibular schwannoma or acoustic neuroma, affects the eighth cranial nerve that contains nerve cells important for balance and hearing. The most common type of benign schwannoma is the acoustic neuroma. When cancerous, these tumors are called malignant schwannomas.

Secondary (Metastatic) Brain Tumors

Secondary brain tumors do not start in the brain. They are also called metastatic brain tumors because they metastasize or travel from another part of the body to the brain. Secondary brain tumors are more common than primary tumors and are malignant. They are caused by cancer cells that originate in the lungs, breasts, skin (melanomas), kidneys, bladder, soft tissue (sarcomas), testicles, and other areas. Some cancers spread to the brain only infrequently (colon cancer), or very rarely (prostate cancer).

Possible Symptoms or Signs of Brain Tumors

Since they grow at various rates, brain tumors often invade or put pressure on normal brain tissue, resulting in symptoms and/or signs that patients, doctors, friends, or loved ones can identify. These symptoms or signs can vary, depending on the area of the brain affected. While mental disorders can also cause similar symptoms, it is advisable to consult a physician if any of the following symptoms occur:

Symptoms or signs generally caused by intracranial pressure:

• The advent of persistent headaches that occur after waking up and usually decrease in severity as the day goes on;
• Vomiting, with or without nausea, usually after waking up, especially if it is more serious in the morning;
• Mental changes, including sluggishness or drowsiness;
• Uncoordinated, clumsy movements, especially when walking;
• Seizures, especially those of recent onset;

Other symptoms and signs, often dependent upon brain area affected:

• Personality or behavior changes;
• Emotional instability or rapid emotional changes;
• Intellectual decline that can include loss of memory, impaired calculating abilities, impaired judgment, etc.;
• Neurological changes that may include impaired or double vision, blindness in one direction, hearing loss or ringing/buzzing in the ear, reduced sensation or weakness in a body area;
• Fever;
• General weakness, lethargy or diminished alertness;
• General ill feeling or malaise;
• Tongue problems, difficulty swallowing, hiccups, or difficulty with speech;
• Inability to control hand movement or presence of hand tremors;
• Impaired sense of smell;
• Impaired sense of touch;
• Confused, unusual or strange behavior;
• Obesity;
• Cessation of menstruation prior to age of menopause age;
• Facial paralysis or muscle weakness that can cause drooping eyelid or one-sided smile;
• Eye abnormalities, including different-sized pupils or uncontrollable movement;
• Temporary cessation of breathing.

Diagnosing Brain Tumors

Brain tumors can difficult to diagnose because symptoms providing clues for physicians, can be tricky to identify with certainty. When a patient experiences symptoms indicating a brain tumor, doctors usually call first for a neurological evaluation to test reflexes, muscle strength, sensation, eye and mouth movement, coordination, alertness, memory, ability to concentrate, changes in vision, and other factors. Symptoms depend on the size of the tumor and on the area of the brain affected. As a tumor grows, it can affect other parts of the brain and cause new symptoms. The location of your tumor is a key factor in the kinds of treatment you may need.

Getting an Accurate Picture

Once a tumor is suspected, the next step in diagnosis is to obtain images of the brain to help pinpoint its location. Your physician can order Magnetic Resonance Imaging (MRI) or a computed tomography (CT or CAT) scan to analyze internal brain structure. Other types of scans are also available to help find the exact location of the tumor and get a more accurate composite of its characteristics. Information from scans is also used to help determine the best treatment.

Other Diagnostic Tools

Sometimes a biopsy, or small sample removed from a tumor, may be needed to assist in making an accurate diagnosis. Once the sample is obtained, it can be evaluated to determine the type of tumor and gauge how aggressive it is. Again, that information can contribute to determining the treatment to be used. It is important to categorize the kinds of cancerous cells that make up a tumor and their rate of growth when deciding upon the treatment approach.

Treating Brain Tumors

Depending on the size of your tumor, its rate of growth and symptoms, your doctor may choose any one of the following treatment options or any combination of them:

Surgery

Simply removing a brain tumor is often the most straightforward method of eliminating it. A surgeon generally removes a piece of the skull to allow access to the brain, replacing the bone after operating. In some cases, it is not possible to remove the entire tumor. Other treatments may be used following a craniotomy.

Radiation Therapy

The cells of many tumors readily die when exposed to radiation, making radiotherapy an important tool for fighting tumors in the brain. This method can be used if the tumor is inaccessible or if it is known to be sensitive to radiation. Radiation therapy generally consists of X or gamma rays aimed at the site of a tumor. Even if surgery has been successful in removing an entire tumor, radiation may be used to kill microscopic cancer cells remaining in surrounding tissue that could spread to other areas of the brain. If the entire tumor cannot be removed, radiation is often recommended to kill the remaining portion of the tumor and/or stop its progression.

Brachytherapy

Brachytherapy is a form of radiation therapy that involves placing a high dose of radiation, often in the form of small radioactive rods, inside or next to the area needing treatment. The radiation source is often placed precisely, using computer guidance, thus maximizing the dosage received by the tumor while minimizing exposure to healthy tissue.

Chemotherapy

Chemotherapy is simply using one or more special chemicals to poison tumor cells, which are more vulnerable to these materials than healthy tissue. Chemotherapy may be used before, during, or after surgery and radiation therapy. Some drugs help other drugs reach the tumor in higher concentrations. Combining chemotherapy with radiation has proved helpful for some high-grade tumors. Chemotherapy can be administered orally, intravenously, by infusion or as a wafer placed in the brain.

Gamma Knife®

A gamma "knife" consists of narrow, highly focused beams of cobalt gamma radiation that can destroy a wide variety of benign and malignant brain tumors and other abnormalities without invasive surgery. This method offers patients fewer side effects and shorter recovery time than conventional surgery. Gamma knife "surgery" usually takes between 30 minutes and three hours and may involve a one-night stay in the hospital or be performed as an outpatient service.

Side Effects of Treating Brain Tumors

Patients can experience side effects when they undergo treatments for brain tumors because healthy brain cells are often damaged when tumors are treated in various ways. The kinds of side effects and their severity vary depending upon the particular treatment involved, its duration, and its dose.

Surgery

Side effects experienced after brain surgery depend on the location of the tumor, the type of operation, and other factors. Edema (swelling) of the brain around the tumor location is common after surgery or other treatments. Pressure on surrounding brain tissue can cause headaches, sleepiness and more serious problems. Steroids can be used to help prevent these kinds of side effects. Patients may often be uncomfortable during the first few days after surgery, but pain can usually be controlled with medicine. The recovery period after surgery varies from patient to patient. In some case, long-lasting neurologic damage may also occur.

Chemotherapy

Chemotherapy drugs are selected because they target fast-growing cancer cells, but other cells in the body also divide rapidly and can be affected, including blood and bone marrow cells, cells that line the stomach and digestive tract, and cells in hair follicles. Side effects can include fatigue, temporary hair loss, nausea/vomiting, diarrhea and mouth sores. Side effects may be more pronounced with elderly patients if they take multiple medications. Medicines and other treatments are available to control or minimize many of these symptoms.

Since chemotherapy affects the function of bone marrow in producing blood cells, patients may experience reduced blood counts. Lower levels of red blood cells can result in anemia and reduce a patient's energy level, even requiring blood transfusions in severe cases. Low platelets may mean patients will bruise or bleed more easily, again requiring transfusions if the condition becomes severe. Finally, fewer antibodies in the blood can make patients more susceptible to infection and fever.

Not every chemotherapy patient experiences all of these symptoms, and they usually diminish during the recovery period or after treatment ends.

Radiation Therapy

Side effects due to radiation therapy vary according to the type of radiation used. They include hair loss, headache, nausea and vomiting, skin irritation, hearing problems, drowsiness and fatigue, fever, and worsening of tumor-related neurologic symptoms. Some patients experience loss of appetite. Mouth sores may make it difficult to eat. Food may even taste differently to some patients, while others may not feel like eating because they are uncomfortable or tired. Those who continue to eat well during cancer treatment are usually more able to handle side effects because they feel better and have more energy.

Radiation may also reduce white blood cell counts, affecting the patient's resistance to infection. Most of these side effects can be treated and controlled and are often not permanent.

Neurologic (brain-related) symptoms are classified into three categories: acute, early delayed (sub-acute), and late

First, acute side effects occur soon after therapy treatments and are caused by brain swelling (edema) resulting from radiation. Other side effects can mimic brain tumor symptoms and may include speech problems, muscle weakness, headache, nausea or double vision.

Second, early delayed effects can occur between one and three months after treatment ends. They can include loss of appetite, sleepiness, lack of energy and an increase in pre-existing neurologic symptoms.

Third, late side effects can occur months or years after treatment and may include a mild or severe decrease in intellect, impaired memory, confusion, personality changes, and alteration of the normal function of the area irradiated.

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