Brain tumors - primary
Highlights
Radiation Therapy Complications
- Radiation therapy in children with cancer increases the risk of new brain and spinal cord tumors, suggests a study in the Journal of the National Cancer Institute. The risk appears to increase along with the radiation dosage. Children who receive radiotherapy before age 5 are especially at risk for second primary tumors.
- Survivors of childhood brain tumors who received cranial radiotherapy as part of their treatment are at risk for later having a stroke, indicates a study in the Journal of Clinical Oncology. The average length of time from brain tumor diagnosis to post-treatment stroke was 14 years.
Radiation Therapy for Elderly Patients
Radiotherapy provides modest improvement in survival for elderly patients (age 70 years and older) with glioblastoma, with no detriment to quality of life or cognition function, according to a 2007 study in the Journal of the American Medical Association.
Temozolomide (Temodar)
The chemotherapy drug temozolomide (Temodar) has become an important and effective treatment for patients newly diagnosed with glioblastoma. However, not all patients respond equally well to this drug. A 2007 study in the journal Neurology suggests that a patients genotype may explain differences in response. Though genetic testing, researchers found that temozolomide works best in people who are missing a particular gene.
Investigational Treatments
- Vorinostat (Zolinza), a cancer drug used for T-cell lymphoma, may help patients with recurrent glioblastoma multiforme, according to research presented at the 2007 annual meeting of the American Society of Clinical Oncology.
- Bevacizumab (Avastin), a targeted therapy drug used for lung and colorectal cancers, may help prolong survival in patients with advanced glioma, indicates a 2007 study in Clinical Cancer Research. Another anti-angiogenesis drug, cediranib (Recentin), may help make glioblastomas more responsive to chemotherapy and radiotherapy, according to recent interim trial results.
- Vitespen (Oncophage), an experimental vaccine for glioma, is showing promise in early clinical trials, suggests research presented at the 2007 meeting of the American Association of Neurological Surgeons.
Introduction
Brain tumors are composed of cells that exhibit unrestrained growth in the brain.

They can be benign (noncancerous, meaning that they do not spread elsewhere or invade surrounding tissue) or malignant (cancerous).
Cancerous brain tumors are further classified as either primary or secondary tumors. Primary tumors start in the brain, whereas secondary tumors spread to the brain from another site such as the breast or lung. (In this report, the term "brain tumor" will refer mainly to primary malignant tumors, unless otherwise specified.)
Benign Tumors
Benign tumors represent half of all primary brain tumors. Their cells look relatively normal, grow slowly, and do not spread (metastasize) to other sites in the body. Benign tumors can still be serious and even life-threatening if they are in vital areas in the brain where they exert pressure on sensitive nerve tissue or if they increase pressure within the brain. While some benign brain tumors may pose a health risk, including risk of disability and death, most are usually successfully treated with techniques such as surgery.
Secondary (Metastatic) Malignant Brain Tumors
A secondary (metastatic) brain tumor occurs when cancer cells spread to the brain from a primary cancer in another part of the body. Secondary tumors are about three times more common than primary tumors of the brain. Usually, multiple tumors develop. Solitary metastasized brain cancers may occur but are less common. Most often, cancers that spread to the brain to cause secondary brain tumors originate in the lung, breast, kidney, or from melanomas in the skin.
Primary Malignant Brain Tumors
A primary malignant brain tumor is one that originates in the brain itself. Although primary brain tumors often shed cancerous cells to other sites in the central nervous system (the brain or spine), they rarely spread to other parts of the body.
Brain tumors are generally named and classified according to the following:
- The normal brain cells from which they originate, or
- The location in which the cancer develops
The biologic diversity of these tumors, however, makes classification difficult, and some experts believe that more specific categories are needed.
Categories of Primary Glioma Brain Tumors by Cell Types
About half of all primary brain tumors are known collectively as gliomas. They are cancerous forms of glial cells, the building-block cells of the connective, or supportive, tissue in the central nervous system. There are several glial cells types from which gliomas form. Their names are:
- Astrocytomas are primary brain tumors derived from astrocytes, which are star-shaped glial cells. Normal astrocytes provide nutrients, support, and insulation for nerve cells and are one of the primary neurologic cells in the body. The malignant astrocytomas called glioblastomas account for 23% of brain tumors and are the most common ones.
- Oligodendrogliomas develop from oligodendrocyte glial cells, which form the protective coatings around nerve cells. Although oligodendrogliomas were thought to represent about 5% of all gliomas, more recent evidence suggests they may comprise about 20% of gliomas. Pure oligodendrogliomas, however, are rare. In most cases they occur in mixed gliomas.
- Ependymomas are derived from ependymal cells, which line the ventricles (fluid-filled cavities) in the lower part of the brain and the central canal of the spinal cord. They constitute about 6% of all primary tumors in the central nervous system. About 30% of these tumors occur in the spinal cord.
- Mixed gliomas contain a mixture of malignant gliomas. About half of these tumors contain cancerous oligodendrocytes and astrocytes.
It should be noted that gliomas may also contain cancer cells derived from brain cells other than glial cells.
Categories of Brain Tumors by Location
Some brain tumors are categorized by their location in the brain. Such tumors often contain gliomas but are also frequently a mixture of different cell types.
Meningiomas. Meningiomas are usually benign tumors that develop in the membranes that cover the brain and spinal cord (the meninges).
They are not technically classified as brain tumors, but they have similar symptoms and develop within the brain. So in practical terms, they are considered brain tumors. In fact, meningiomas comprise 20% of all primary brain tumors. They occur more often in women than in men. Most grow very slowly, and the majority of people who have them never know they are present. Malignant forms called anaplastic meningiomas and hemangiopericytomas are less common and are difficult to remove surgically.
Cerebral Astrocytomas. Gliomas that develop inside the brain often occur in the cerebral hemispheres (the right and left sides of the brain). In such cases, they are referred to as cerebral astrocytomas. Gliomas sometimes occur in another part of the brain, called the cerebellum. The cerebellum is responsible for balance and coordination. In such cases, the term cerebellar astrocytoma is used.
Brain Stem Gliomas. Brain stem gliomas develop in the lowest portion of the brain. The brain stem connects the cerebrum (the higher centers of the brain) to the spinal cord. The brain stem is thought to be the primitive brain because it controls the most basic functions.
The brain stem consists of three primary parts:
- The medulla regulates breathing, swallowing, blood pressure, and heart rate.
- The pons links the cerebellum to the cerebrum.
- The midbrain helps control vision and hearing.
Medulloblastomas. Medulloblastomas are always located in the cerebellum, which is at the base and toward the back of the brain. They represent about 3% of all brain tumors.
Pituitary Tumors. Pituitary tumors comprise about 10% of primary brain tumors and are often benign, slow-growing masses in the pituitary gland.
Other Brain Tumor Locations. Optic nerve gliomas occur in the optic nerve, which is located behind the eye. Acoustic neuromas make up 7.5% of brain tumors.
Symptoms
Brain tumors produce a variety of symptoms, ranging from headache to stroke. They are great mimics of other neurologic disorders. Symptoms occur if the tumor directly damages the nerves in the brain or central nervous system or if its growth imposes pressure on the brain. Some gliomas develop gradually, and symptoms may be subtle for a long time, making an early diagnosis difficult.
Headache
Headache is probably the most common symptom of a brain tumor. It should be strongly emphasized, however, that everyone has headaches, and they rarely represent an underlying brain tumor. Headaches caused by brain tumors may vary depending on the location, and many different features.
- Steady and worse upon waking in the morning and clears up within a few hours
- Persistent non-migraine headache that occurs while sleeping and is also accompanied by at least one other symptom (such as vomiting or confusion)
- May or may not be throbbing, depending on location of the tumor
- Accompanied by double vision, weakness, or numbness
- May worsen with coughing or exercise or with a change in body position
- Sometimes accompanied by neck pain
Gastrointestinal Symptoms
Gastrointestinal symptoms, including nausea, are also common. Nausea and vomiting, in fact, often occur in children with brain tumors and in all people with brain stem cell tumors.
Seizures
Seizures occur in between 15 - 95% of patients, depending on the location of the tumor.
- Tumors are more likely to be localized and affect one area of the brain. In such cases they can cause partial seizures. In this case, a person does not lose consciousness but may experience confusion, jerking movements, tingling, or odd mental and emotional events.
- Generalized seizures, which can cause loss of consciousness, are less common, since they are caused by disturbances of nerve cells in diffuse areas of the brain.
Mental Changes
Sometimes the only symptoms are mental changes, which may include the following:
- Memory loss
- Impaired concentration
- Problems with speech and reasoning
- Increased sleep
Other Significant Symptoms
- Gradual loss of movement or sensation in an arm or leg
- Unsteadiness
- Unexpected visual disturbance (especially if it is associated with headache), including vision loss (usually of peripheral vision) in one or both eyes or double vision
- Hearing loss with or without dizziness
- Speech difficulty
Symptoms Associated with Specific Tumors
Specific symptom syndromes may help identify the tumor. The following are some examples.
Symptoms of Brain Stem Gliomas. Sudden onset of symptoms that include vomiting (usually just after waking), a clumsy walk, muscle weakness on one side of the face, difficulty in swallowing, slurred or nasal speech, as well as impaired hearing or vision.
Symptoms of Glioblastoma Multiforme. Rapid onset and worsening of symptoms that include headaches, seizures, memory loss, and changes in behavior.
Life-Threatening Syndromes
The below symptoms indicate an emergency condition and require immediate medical attention:
- Pupil dilation
- A fixed gaze
- Paralysis on one or both sides of the body
- Blindness or defective vision in one eye
Risk Factors
Nearly 360,000 people in the U.S. are living with brain cancer. Men are at higher risk than women for most brain tumors. Primary malignant brain tumors are still uncommon and represent only 1.3% of all cancers diagnosed in the United States and 2.4% of all deaths due to cancer.
Primary brain cancers are rare, occurring in slightly more than 11 people per 100,000 per year. There has been some evidence of a growing incidence of brain cancer among the elderly since the 1980s. The increase, however, is most likely due to the rise in incidence of non-Hodgkin's lymphomas -- which can occur in the brain. When this malignancy is eliminated, any increase in other tumors is not significant.
Age
The average age of diagnosis for brain tumors is 57, and about 90% of primary brain tumors occur in adults. These tumors can develop at all ages, usually peaking in two age groups.
- In adults, ages 55 - 65
- In children, ages 3 - 12
Risk Factors in Children. Tumors in the central nervous system are now the most common primary cancers in children, but they are still rare. An estimated 3,110 benign or malignant brain tumors are expected to be diagnosed in children each year. Brain tumors in children are more likely to occur in the cerebellum, the midbrain, or the optic nerve.
The incidence has increased over the past years, but there is some evidence that this increase is only due to better diagnostic procedures. The mortality rate has actually decreased. Researchers have attempted to uncover risk factors for childhood brain cancer. There may be some association between a higher risk and the following conditions:
- Children treated with radiation to the head for leukemia and who have a specific genetic defect may face a high risk for brain cancer. (It should be noted that for children without this defect, the risk is very small.)
- Having parents with specific cancers. (According to one study, having parents with nervous system cancers, colon cancer, or cancer in the salivary glands increased the risk of specific brain tumors in their children.)
Ethnicity
The risk for primary brain tumors in Caucasians is higher -- as much as twofold depending on type -- than in African-Americans.
Environmental or Occupational Risk Factors
Radiation Exposure. People who receive radiation therapy to the head during cancer treatment have an increased risk of developing brain tumors 10 - 15 years later. Workers in the nuclear industry are also at increased risk.
There is no evidence that electromagnetic field exposure from power lines or household appliances poses any risk. Several recent epidemiological studies, including a 2006 study in the British Medical Journal, found that cell phones, cordless phones, and wireless devices are also safe and do not increase the risk for gliomas.
Chemical and Metals in Brain Tumors. High exposure to numerous metals and chemicals have been associated with brain tumors:
- Industrial chemicals, including vinyl chloride and petroleum products
- Lead, arsenic, or mercury exposure
- Exposure to pesticides. A major study of pesticides is underway, but results are not in yet. A 2003 study indicated that parental exposure to pesticides or herbicides did not appear to be important in increasing risk for brain cancer in their children.
Brain cancer is uncommon, and, over the course of their lifetime, many people are exposed to these chemicals, many of which are very common. To date, there has been no clear evidence that implicates any specific industrial chemical or metal.
Organ Transplantation
One study reported a higher risk for brain cancers in patients who had undergone organ transplantations. Researchers believed that the drugs used to suppress the immune response after the procedures may increase the risk.
Medical Conditions Associated with a Lower Risk for Brain Tumors
One study reported lower risks for brain cancers in individuals with allergies and autoimmune diseases (such as type 1 diabetes). Autoimmune diseases were also associated with a lower risk for meningiomas. The cause of this possible association remains unknown.
Studies have also found an association between lower risk for gliomas and a history of infection with varicella zoster, the virus that causes chicken pox and shingles.
Causes
Genetics
Only 5 - 10% of primary brain tumors are associated with genetic disorders. These inherited conditions and associated genes include:
- Von Recklinghausen disease, also called neurofibromatosis 1 (NF1 gene) and neurofibromatosis 2 (NF2 gene)
- Turcot's syndrome (APC gene)
- Gorlin syndrome, also called basal cell naevus syndrome (PTCH gene)
- Tuberous sclerosis (TSC1 and TSC2 genes)
- Li-Fraumeni syndrome (TP53 gene)
Certain types of brain tumors are specifically linked with these genetic conditions. For example, neurofibromatosis 1 is associated with about 15% of cases of pilocytic astrocytomas, the most common type of childhood glioma. Neurofibromatosis results from defects in the tumor suppressor genes NF1 and NF2. Li-Fraumeni syndrome results from mutations in the tumor suppressor gene TP53. These mutations affect the production of tumor suppressor protein p53.
Tumor suppressor genes regulate cell division and help repair DNA damage. When mutations that affect protein encoding occur, unregulated cell division and growth can lead to the development of a tumor. Tumor suppressor genes are sometimes described as being in a tug-of-war with cancer-causing genes called oncogenes. Oncogenes derive from mutations or overexpressions of proto-oncogenes. Proto-oncogenes encode for proteins that regulate cell growth and differentiation. When proto-oncogenes become oncogenes, normal cells start to grow uncontrollably. Cancer can occur when tumor suppressor genes are turned off, or when oncogenes are turned on.
Many different oncogenes are involved in cancer. Growth factors are a particularly important type of oncogene associated with brain tumors. Growth factors attach to receptors (connectors) that stimulate cell growth. Epidermal growth factor receptor (EGFR) has been shown to play a role in high-grade brain tumors such as glioblastoma multiforme. In 2007, scientists identified insulin-like growth factor binding protein (IGFBP2) with an oncogene that may be associated with the development of astrocytoma and oligodendroglioma.
Knowing the molecular origin of a brain tumor may help determine the treatment course, both for standard chemotherapy and "targeted therapy" biologic drugs. For example, patients with tumors marked by high EGFR proliferation may benefit from treatment with the EGFR kinase inhibitor drugs gefitinib (Iressa) or erlotinib (Tarceva).
Most genetic abnormalities that cause brain tumors are not inherited but occur as a result of environmental or other factors that affect genetic materials (DNA) in the cells. Researchers are studying various environmental factors (viruses, hormones, chemicals, radiation) that may trigger the genetic disruptions that lead to brain tumors in susceptible individuals. They are also working to identify the specific genes that are affected by these environmental triggers. For example, in a 2007 study, scientists proposed that genetic susceptibility may explain why some people develop meningioma, a rare type of brain tumor, following exposure to ionizing radiation. Future investigations will hopefully identify the specific genes involved and help determine which people would potentially be most at risk.
Prognosis
About 13,100 people die from cancerous brain tumors each year. Recent advances in surgical and radiation treatments have significantly extended average survival times and can reduce the size and progression of malignant gliomas. In general, survival rates are highest in younger people and lowest in the elderly.
Five Year Survival Rates by Age Group | |
Age | Survival Rates |
0 - 19 years | 63.1% |
20 - 44 years | 50.4% |
45 - 64 years | 14.2% |
Over 65 | 4.9% |
Data From: 2002 - 2003 Primary Brain Tumors in the United States Statistical Report. Fact Sheet (1973- 1999 data). Brain Tumor Registry of the United States www.cbtrus.org/factsheet/factsheet.html. | |
In general, studies are reporting that patients who survive the first 2 years after a diagnosis of a brain tumor have at least a 70% chance of surviving for at least 5 years. The best recent progress has been made for:
- Medulloblastomas in both children and adults. Long-term survival rates are now about 60% in children after treatment for medulloblastomas, the most common malignant brain tumor in this age group. (New treatments, however, may significantly improve these rates.)
- Nonmalignant astrocytomas and oligodendrogliomas in adults.
Unfortunately, the majority of primary brain tumors, notably anaplastic astrocytomas and glioblastoma multiforme, are only rarely curable.
Specific Effects of Tumors on Function
The specific effects of tumors on the brain can cause seizures, mental changes, and mood, personality, and emotional changes. Such effects can be devastating to the patient and the caregivers. Numerous treatments are available that help alleviate these complications, and patients and family members should discuss these with their doctors.
Diagnosis
A neurological exam is usually the first test given when a patient complains of symptoms that suggest a brain tumor. The exam includes checking eye movements, hearing, sensation, muscle movement, sense of smell, and balance and coordination. The doctor will also test mental state and memory.
Imaging Techniques
X-rays of the skull were once standard diagnostic tools but are now performed only when more advanced procedures are not available. Advanced imaging techniques have dramatically improved the diagnosis of brain tumors in recent years.
Magnetic Resonance Imaging. Magnetic resonance imaging (MRI) is the gold standard for diagnosing a brain tumor. It does not use radiation and provides pictures from various angles that can enable doctors to construct a three-dimensional image of the tumor. It gives a clear picture of tumors near bones, smaller tumors, brainstem tumors, and low-grade tumors. MRI is also useful during surgery to show tumor bulk, for accurately mapping the brain and for detecting response to therapy.

A variant called magnetic resonance spectroscopy (MRS) is capable of providing information on the activity of the brain using magnetic resonance imaging. MRS is proving to be accurate for distinguishing dead (necrotic) tissue caused by previous radiation treatments from recurring tumor cells in the brain, a difficult diagnostic issue.
Computed Tomography. Computed tomography (CT) uses a sophisticated x-ray machine and a computer to create a detailed picture of the body's tissues and structures. It is not as accurate as an MRI and does not detect about half of low-grade gliomas. It is useful in certain situations, however. Often, doctors will inject the patient with an iodine dye, called contrast material, to make it easier to see abnormal tissues. A CT scan helps locate the tumor and can sometimes help determine its type. It can also help detect swelling, bleeding, and associated conditions. In addition, computed tomography is used to check the effectiveness of treatments and watch for tumor recurrence.
Positron Emission Tomography. Positron emission tomography (PET) provides a picture of the brain's activity rather than its structure by tracking substances that have been labeled with a radioactive tracer. As with magnetic resonance spectroscopy (MRS), it is also able to distinguish between recurrent tumor cells from dead cells or scar tissue, although MRS is more widely available. PET is not routinely used for diagnosis, but it may supplement MRIs to help determine tumor grade after a diagnosis. Data from PET may also help improve the accuracy of newer radiosurgery techniques.
Other Imaging Techniques. Numerous other advanced imaging techniques may be used for specific purposes, if available or under investigation.
- Single photon emission tomography (SPECT) is similar to PET but is not as effective in distinguishing tumor cells from destroyed tissue after treatments.
- Magnetoencephalography (MEG) scans measure the magnetic fields created by nerve cells as they produce electrical currents.
- Cerebral angiography involves x-rays of blood vessels in the brain. A long, thin tube (catheter) is threaded through blood vessels from a distant site to the brain, and a radiopaque substance (a substance that is impenetrable to x-rays) is injected through it. The role of angiography in glioma is usually limited to planning surgical removal of a tumor suspected of having a large blood supply.
- Radionuclide brain scintigraphy uses a radioactive substance that is administered and absorbed by capillaries in the tumor, which are then viewed using imaging techniques.
- Digital holography, a new technique that provides full three-dimensional mapping, is under investigation.
Lumbar Puncture (Spinal Tap)
A lumbar puncture is used to obtain a sample of spinal fluid, which is examined for the presence of tumor cells. A computed tomography (CT) scan or magnetic resonance imaging (MRI) should generally be performed before a lumbar procedure to be sure that the procedure will be safe.
Biopsy
A biopsy is a surgical procedure in which a small sample of tissue is taken from the suspected tumor and examined under a microscope for malignancy. The results of the biopsy also provide information on the cancer cell type.
In some cases, such as brain stem gliomas, a biopsy might be too hazardous because removing any healthy tissue from this area can affect vital functions. In such cases, diagnosis must rely on less invasive and possibly less accurate measures. Of promise is the stereotactic technique (also called stereotaxy), which uses computers to provide three-dimensional views of very small areas. This may allow precise biopsies of cancer cells without affecting healthy brain tissue. Expertise in this technique is extremely important, however, and the technique is not widely available.
Determining a Prognosis
The survival rates in people with brain tumors depend on many different variables:
- Whether the tumor is malignant or benign
- Cancer cell type and location (location affects whether the tumor can be removed surgically or not)
- The tendency to spread and the growth rate (tumor grade)
- Patient's age
- Patient's ability to function
- Duration of symptoms
The outlook is poorer in the very youngest and very oldest patients, although younger patients who survive 2 years after diagnosis have a much better outlook than older patients.
Grading Tumors. Malignant primary brain tumors are classified according to tumor grade. Grade I is the least cancerous, and Grades IV and V are the most dangerous. Grading a tumor attempts to predict its tendency to spread and its growth rate. It is based on the appearance of the tumor cells as seen under a microscope.
- Lower-grade (I and II) tumor cells are well defined and almost normal-shaped. (Some primary low-grade brain tumors are curable by surgery alone, and some are curable by surgery and radiotherapy. Low-grade tumors tend to have the most favorable survival rates and high-grade the least. However, this is not always the case. For example, some low-grade II gliomas are at very high risk for progression.)
- Higher-grade (III and IV) tumor cells are abnormally shaped and are more diffuse, which indicates more aggressive behavior. (High-grade brain tumors usually require surgery, radiotherapy, chemotherapy, and possibly investigational treatments.)
- In tumors that contain a mixture of different-grade cells, the tumor is graded using the highest-grade cells in the mixture, even when there are very few of them.
Biologic Markers. Elevated levels of certain cancer-associated molecules or compounds may be correlated with prognosis. For example, evidence of genetically mutated p53 indicates a poorer prognosis in younger patients with glioblastoma multiforme.
Elevations of epidermal growth factors (EGF) or vascular endothelial growth factors (VEGF) suggest aggressive tumors. High levels of the receptor for EGF (EGFR), in fact, are found in 70% of glioblastoma specimens.
Genetic Profiles of Cancer Cells. Analyses that identify genetic types may soon help clinicians determine if patients with specific brain tumor cells might respond better to one treatment than another. For example, specific genetic profiles of oligodendrogliomas can help predict how patients respond to nitrosourea alkylating drugs such as carmustine. Genetic variation tests are also being used to determine how patients may respond to epidermal growth factor receptor (EGFR) kinase inhibitors, such as erlotinib (Tarceva) and gefitinib (Iressa).
A genetic profile can also help give doctors a better idea of a patients prognosis and survival. In a 2006 study of patients with anaplastic oligodendroglioma, the status of specific chromosomal deletions within tumors was a better predictor of survival than which kind of treatment patients received. In fact, the researchers suggested that gliomas be classified according to chromosomal deletion status, and recommended that chromosomal testing be a regular part of diagnosis and treatment decisions.
Common Brain Tumors
Common Brain Tumors: Astrocytomas | ||
GENERAL DESCRIPTION OF ASTROCYTOMAS: Derived from star-shaped glial cells called astrocytes. | ||
Grade and Subtype | Description of Subtypes | Usual Treatment |
Low-Grade (Usually I) Astrocytomas. Pilocytic gliomas. | Pilocytic gliomas occur mostly in children. Tumors are well differentiated. Cells are relatively normal and rarely metastasize. They grow relatively slowly. Pilocytic astrocytomas have the highest 5-year survival rates (greater than 70%). However, even well differentiated astrocytomas are life threatening if they are inaccessible. | Cancer may sometimes be completely removed through surgery, particularly if it occurs in the cerebellum. For recurrence or residual tumors, reoperation, radiotherapy, or chemotherapy may be given, depending on the circumstances. Repeat surgery for cerebellar astrocytoma is often very successful. For those who fail radiotherapy and chemotherapy, investigative drugs are used. |
Low-Grade (II) Astrocytomas. Fibrillary, protoplasmic, and protoplasmic astrocytomas. Some pleomorphic xanthoastrocytomas. | Tumors are well differentiated. Cells are relatively normal and less malignant than those in higher grades. They grow relatively slowly but can spread. Survival rates average 5 years, but people can survive for a decade or more. Pleomorphic xanthoastrocytomas have a relatively favorable prognosis, but can recur and demonstrate aggressive clinical behavior. Low-grade astrocytomas generally occur in young adulthood, with a peak incidence in 30s and 40s. | Surgery, if possible, plus radiotherapy. Surgery alone in certain children, if possible. Trials on postoperative radiotherapy include the following: radiotherapy with or without chemotherapy; low-versus-high radiotherapy doses (studies suggest results are the same and high-dose causes more side effects); deferring radiotherapy until tumor progresses and symptoms occur. (A major study confirmed earlier ones that suggest that this approach has the same 5-year survival benefits -- about 65% -- as immediate postoperative radiotherapy.) |
Malignant (High-grade III and IV) Astrocytomas. Anaplastic astrocytoma (gemistocytic and some pleomorphic xanthoastrocytomas). Usually mid-grade (III). | Tumors grow more rapidly than lower grades and infiltrate other nearby healthy cells. Not well-differentiated. Five-year survival rates are about 30%. Recurrence is common. | Treatment same for all high-grade malignant astrocytomas. Surgery, with removal of as much of tumor as possible followed by radiotherapy, with or without chemotherapy. The addition of chemotherapy, particularly being able to take more than 6 cycles, appears to improve survival rates. Carmustine (BCNU) most effective drug at this time. Other drugs and treatment sequences are under investigation. For example, temozolomide is showing promise for many patients, including the elderly. Topotecan may also be useful with other drugs or with radiation. For recurring gliomas, surgery with placement of wafers that release carmustine (Gliadel wafers) is the only proven beneficial therapy to date. Combinations, such as procarbazine and carmustine, provide benefits for recurrent anaplastic astrocytomas. Single drugs may be less toxic and as helpful for other recurrent gliomas. Temozolomide has been approved in Europe for high-grade recurrent gliomas and is proving to be beneficial. Other trials include the following: drugs that block small molecules involved in tumor growth; radioimmunotherapy using monoclonal antibodies; advanced radiotherapy techniques; intraarterial chemotherapy. |
High-grade (IV and V). Glioblastoma (notably glioblastoma multiforme or GBM). | Very rapidly growing tumors that spread quickly. Represents about 25% of all primary brain tumors. Most common in older adults (over age 55) and affect more men than women. Recurrences are common in patients who achieve long-term survival. | |
Common Brain Tumors: Ependymomas | ||
GENERAL DESCRIPTION OF EPENDYMOMAS: Derived from cells that line the ventricles (fluid-filled brain cavities) and spinal cord central canal. Do not usually spread into normal brain tissue. Can block exits for cerebrospinal fluid and cause hydrocephalus. They constitute about 4% of all central nervous system tumors in adults and 10% of these tumors in children. About 30% of ependymomas develop in the spinal column. | ||
Grade and Subtype | Descriptions of Subtypes | Usual Treatment |
Low-grade (I). Myxopapillary ependymoma (found in the spine). Subependymoma (found in one of the ventricles). | No or very slow growth. In addition to grade, risk is also based on location of the tumor. Tumors on the spinal cord are more accessible than those in the fourth ventricle or in the middle of the lower back portion of the brain. | Can often be removed and cured with surgery, particularly those on spinal cord. Radiation may be needed. Chemotherapy (avoid radiation, if possible) in children under age 6). |
Low-grade (II). Papillary, cellular, and clear cell ependymomas. | Slow growth. Usually affect adults. | Surgery alone or followed by radiotherapy. For those who fail radiotherapy, possible use of nitrosourea-based chemotherapies or investigative drugs. |
Grade III. Anaplastic ependymomas. | Spreads to the spinal fluid. | Surgery followed by radiotherapy to brain and spinal cord. Possible shunt. |
Grade IV. Primitive neuroecto-dermal tumor (PNET). Composed of malignant forms of early, undeveloped nerve cells called neuroblasts. (This malignancy is also referred to as neuroblastoma.) | Very rare, but more common in children. Primitive nerve cells that grow very rapidly. Usually occur in cerebellum. | Surgery followed by radiotherapy to brain and spinal cord. Chemotherapy in young children. Investigative high-dose chemotherapy with stem cell rescue for children with relapsed cancer. |
Common Brain Tumors: Oligodendrogliomas | ||
DESCRIPTION OF OLIGODENDROGLIOMAS: They develop from oligodendrocyte glial cells. These cells form the protective coatings around nerve cells. Pure cell types are rare. Most often occur in mixed gliomas. Categorized as either low- or high-grade. Most are low-grade II. | ||
Description of Grade | Usual Treatment | |
Low-grade: Low grade difficult to tell from astrocytomas, although they are usually calcified. Very likely to bleed. Usually spread along nerve pathways of the brain and spine and rarely outside this area. In spite of difficulty in removing surgically, in some patients survival can be 30 - 40 years. Usually have better prognosis than astrocytomas of equal grade. Occur mostly in middle-aged adults, although there is also a small peak of incidence in children. | Treatment usually delayed until progression causes symptoms. Surgery to remove whole tumor. Radiotherapy often follows in all adults over age 40 or in anyone in which tumor cannot be completely removed. Solid evidence is lacking on this approach, however, and there is some debate on its benefits. Trials using chemotherapy after radiation are promising. Two-thirds of patients respond to PCV (combination of procarbazine, lomustine and vincristine.) Sustained remissions averaging 16 years often achieved. Pure oligodendrogliomas respond better than mixed gliomas. Temozolomide is showing promise as second-line treatment. Others under investigation. Trials of additional chemotherapy for less well-differentiated tumors or for residual tumors after surgery. | |
High-grade. Anaplastic oligodendrogliomas. | Immediate treatment. Surgery to remove the whole tumor, if possible. Radiation typically follows surgery. Chemotherapy treatments either before or with radiation. Standard drugs are limited. Experts recommend trying investigative drugs. Temozolomide and retinoic acid may be useful. Possible additional drugs include melphalan, thiotepa, carboplatin, cisplatin, and etoposide. (Numerous biologic markers may help identify specific oligodendrogliomas that will respond better or worse to specific treatments.) | |
Common Brain Tumors: Mixed Gliomas | |
GENERAL DESCRIPTION OF MIXED GLIOMAS: Mixed gliomas contain a mixture of malignant gliomas. About half of these tumors contain cancerous oligodendrocytes and astrocytes. | |
Grade | Usual Treatment |
Grade determined by the highest-grade cell present in the tumor. | Same as for oligodendroglioma. |
Some Common Brain Tumors by Location | ||
Brain Tumors | Description | Usual Treatment |
Meningiomas | They are found in the membranes around the brain and spinal column. They are usually benign and rarely invasive. In such cases, long-term outlook is very favorable. (Malignant forms, anaplastic meningiomas, and hemangiopericytomas are uncommon and occur in about 2% of cases.) | Usually watchful waiting. Aggressive surgery the treatment of choice, if possible, although 20% recur after 10 years. Malignant forms and those at the base of the skull difficult to impossible to remove surgically. Stereotactic radiosurgery or fractionated external beam radiotherapy showing promising results for some patients. |
Cerebellar astrocytomas (located in cerebellum) | Located in the cerebellum. Usually low-grade, but depends on cell type. If surgical removal is complete, up to 90% survival rates. More common in children than adults. | Surgery primary treatment. Radiotherapy if removal is incomplete. |
Brain Stem Gliomas | About 60 - 70% of brain stem tumors are diffuse, which are likely to spread and have a rapid onset of symptoms. Focal tumors tend to be solid or cyst-like. They generally develop gradually. Occurs in both children and young adults. | Radiation is usual treatment. Tumors in this area are rarely removed surgically since the nerve tissue in this area is responsible for vital life functions. Slow-growing tumors may only require watchful waiting. Trials using advanced radiotherapy techniques, gene therapy, immunotherapy, and other experimental drugs. |
Medulloblastomas | Occurs in cerebellum (the lower portion of the brain), brainstem, and spinal cord. Usually fast-growing aggressive cells. Most common brain tumors in children and young people, causing between 15 - 20% of brain tumors. With aggressive therapy, in children 5-year survival rates between 60 - 80%. In patients who survive for 2 years after diagnosis, long-term survival rate is nearly 80%. | Treatment is usually surgery and radiotherapy followed by chemotherapy. A 2005 study found that a combination chemotherapy regimen may replace radiation for very young children. A 2006 study suggested that radiation and chemotherapy doses should be adjusted based on disease severity. |
Optic Tract Gliomas | Spread along the optic nerve. Usually slow growing. Most often in children under age 10. Children with these tumors often have vision and hormonal problems. | Usually surgery if one eye is involved. Possible chemotherapy or radiation. |
Treatment
The approach for treating brain tumors is to reduce the tumor as much as possible using surgery, radiation treatment (also called radiotherapy), chemotherapy, or investigative procedures. Such treatments are used alone or, more commonly, in combinations. With some very slow-growing cancers, such as those that occur in the midbrain or optic nerve pathway, patients may be closely observed and not treated until the tumor shows signs of growth. The intensity, combination, and sequence of these treatments depends on the glioma subtype, its size and location, and patient age, health status, and medical history.
Recent advances in surgical and radiation treatments have significantly extended average survival times compared to those of standard therapy. Investigative treatments, such as monoclonal antibodies, are also showing promise. Patients or their caretakers should discuss all options thoroughly with a specialist in brain cancer. Different specialists may be needed to help manage symptoms.
Emotional Support
Because of the low-cure rates of most malignant brain tumors, support for the patients and their families is a critical component of treatment and management. In response to one survey of patients with gliomas, experts made several recommendations to help both patients and caregivers:
- Any physical impairment that could benefit from home equipment or physical therapy should be identified and treated.
- Patients should discuss emotional as well as physical issues with their doctors. Depression, for instance, can be medically treated. Caregivers should also seek help for the inevitable stress, depression, and tension arising from their difficult role.
- Relaxation techniques, meditation, and spiritual resources can be extremely helpful. Support groups are beneficial, but experts recommend separate groups for patients and their families.
Surgery
Surgery is usually the first step in treating most brain tumors. In some cases, however, such as most brain stem gliomas, it may be too dangerous to perform surgery. The object of most brain tumor surgeries is to remove or reduce as much of its bulk as possible. By reducing the size, other therapies, particularly radiotherapy, can be more effective. (Although there have been significant advances in brain surgeries, some experts argue that in high-grade gliomas extensive surgery may not improve survival rates at all and patients are best served by radiation therapy.)
Craniotomy
The standard procedure is called craniotomy.
- The neurosurgeon removes a piece of skull bone to expose the area of brain over the tumor.
- The tumor is located and then removed.
There are various surgical options for breaking down and removing the tumor. They include:
- Standard surgical procedures
- Laser microsurgery (which produces great heat and vaporizes tumor cells)
- Ultrasonic aspiration (which uses ultrasound to break the glioma tumor into small pieces, which are then suctioned out)
Relatively benign, grade I gliomas may be treated only by surgery. Some controversy exists over whether surgery for low-grade astrocytomas improves survival, although insufficient research has been conducted to prove its benefits for these gliomas. Most malignant tumors require additional treatments, including repeat surgery.
The surgeon's skill in removing the tumor as completely as possible is critical to survival. No one should be shy about asking the surgeon the number of similar procedures they have performed. (Asking for complication rates may not be useful, since a very experienced surgeon might operate on many high-risk patients.)
Additional Procedures to Enhance Brain Surgery
In most cancers outside the brain, surgical removal of a tumor usually involves taking out surrounding healthy tissue to be sure all cancer cells are gone. In the brain, however, removing healthy nearby nerve tissue can be as disastrous for the patient as the cancer itself. Special techniques have been developed to allow maximum removal of tumors while protecting healthy brain cells.
Stereotaxy. Stereotaxy has become a useful adjunct to both surgery (stereotactic surgery) and radiotherapy (stereotactic radiotherapy).
Cortical Localization. Cortical localization, or stimulation, uses a probe that passes a tiny electrical current to delicately stimulate a specific area of the brain. This produces a visible response of the body part (such as a twitch in a leg), which the stimulated region of the brain controls. The surgeon then knows to avoid those areas during the operation.
Image-Guided Surgery. Image guided surgery uses a three-dimensional picture of the patient's brain derived from computed tomography (CT) or magnetic resonance imaging (MRI) scans. An advanced technique called high-field interventional MR imaging (iMRI) is particularly accurate in identifying the tumor, but it is not widely available. The image, with various views of the brain, is displayed on a monitor in the operating room. During surgery, as the surgeon's instrument touches a part of the brain, a camera sends the image to a computer, which calculates the position of the surgical tool and displays it in its proper location on the 3-D image. The surgeon then can look at the monitor and see what structures to avoid.
Magnetic-Tipped Catheters. Neurosurgeons are investigating a technique in which external magnetic fields direct a magnet-tipped flexible catheter to the tumor site through a path that avoids harming certain important areas of the brain.
Heparin. Heparin, a blood-thinning drug, should be given at the time of surgery to help prevent blood clots.
Radiotherapy
Radiotherapy plays a central role in the treatment of most brain tumors, whether benign or malignant.
Radiotherapy after Surgery. Even when it appears that the entire tumor has been surgically removed, microscopic cancer cells often remain in the surrounding brain tissue. Radiation targets the residual tumor with the goal of reducing its size or stopping its progression. If the entire tumor cannot be removed safely, postoperative radiotherapy is often recommended. Even some benign gliomas may require radiation, since they may be life-threatening if their growth is not controlled.
Radiotherapy When Surgery Is not Appropriate. Radiotherapy may be used instead of surgery for inaccessible tumors or for tumors that have properties that are particularly responsive to radiotherapy.
Radiotherapy and Chemotherapy (Radiochemotherapy). Combining chemotherapy with radiotherapy is beneficial in some patients with high-grade tumors.
Specific Radiation Treatments
Various radiation treatments are now available.
Conventional radiotherapy uses external beams aimed directly at the tumor and is usually recommended for large or infiltrating tumors. It begins about a week after surgery and continues 5 days per week for 6 weeks. Older adults tend to have a more limited response to external-beam radiation therapy than younger people. According to a 2007 study in the New England Journal of Medicine, radiotherapy leads to a modest improvement in survival in elderly patients (70 years or older) with glioblastoma, and causes few negative impacts on quality of life or cognition.
For tumors that are highly localized, the radiation therapist has a choice of other radiation treatments:
- Brachytherapy (also called interstitial radiation) uses radioactive "seeds" implanted directly in the tumor site. It is used as a booster to external beam radiation for patients with malignant astrocytoma. Brachytherapy appears to prolong survival in some aggressive gliomas. It may also be a safe and effective treatment for some children.
- Intensity-modulated radiation therapy (IMRT) uses high-dose radiation beams that conform to the three-dimensional shape of the tumor.
- Hyperfractionated radiation uses many small radiation doses to deliver a high total dosage of radiation.
- A balloon catheter (GliaSite) that delivers radiation to the tumor cavity after surgery is showing promise.
Stereotactic Radiosurgery
Stereotactic radiosurgery has been developed to allow highly targeted radiation to be delivered directly to the small tumors while avoiding healthy brain tissue. The term radiosurgery is used because the destruction is so precise that it acts almost like a surgical knife. Some studies suggest that stereotactic radiosurgery improves survival, even in patients with the highly aggressive glioblastoma multiforme brain cancer. The procedure is being tested to boost standard radiotherapy.
Benefits of Stereotaxy. There are numerous benefits for stereotaxy:
- Stereotaxy allows precisely focused, high-dose beams to be delivered to gliomas less than 1.25 inch in diameter.
- Investigators have found that stereotactic radiosurgery can help them reach small tumors located deep in the brain that were previously considered inoperable.
- Sometimes with stereotaxy only a single treatment may be needed.
- Unlike traditional radiotherapy, stereotactic radiotherapy can be repeated, so it is useful for recurrent tumors when a patient has already received standard radiation treatments.
- Combining stereotaxy with techniques that gauge speech and other mental functions in patients who are awake during the procedure can allow removal of brain tissue with a lower risk for complications in areas that affect such functioning.
The Planning Procedure. Stereotactic radiosurgery usually begins with a series of steps designed to plan the radiation target:
- First, the patient is given a local anesthetic. In the standard operation, the patient's head must be totally immobilized by screwing a device known as a stereotactic frame into the patient's skull. (The frame procedure is effective only on brain tumors that have regular margins.) The frame is removed as soon as the whole procedure has been completed (about 3 - 4 hours).
- A three-dimensional map, usually using magnetic resonance imaging (MRI) scans, is made of the patient's brain.
- A computer program calculates dosage levels and specific areas for radiation targeting.
Advanced imaging techniques are now allowing frameless stereotaxy, which eliminates the frame and may be effective on more tumors. For example, high-field interventional MR imaging (iMRI) uses a guidance system based on cruise-missile technology to calculate the slightest variations in movements of the head and the location of the tumor relative to these movements. These calculations are then used to target the radiation beams directly on the tumor, even if the patient's head is moving slightly.
Delivery of Radiation Beams. Once the preliminary planning stage has been completed, treatment begins. Several advanced machines, such as the gamma knife, adapted linear accelerator (LINAC), and cyclotron, are being used with stereotaxy and can deliver very focused beams of radiation. Actual treatment takes 10 minutes to 1 hour.
- The gamma knife uses gamma rays that are sent from multiple points to converge at a single point on the tumor. Although each gamma-ray beam is very low dosage, when the beams converge, the intensity and destructive power is very high. The gamma knife is limited to very small tumors and so is generally useful as a booster after standard radiation, surgery, chemotherapy, or combinations.
- The linear accelerator (LINAC) produces photons (positively-charged atomic particles) in patterns that are matched to the tumor shape. The patient is positioned on a bed that can be moved to allow flexible positioning. It allows treatment over multiple sessions of small doses (fractionated stereotactic radiotherapy), instead of a single session. This means that larger tumors can be treated.
- The cyclotron is basically an atom smasher, which produces protons that can be directed toward the tumor. As part of this procedure, some researchers are using boron neutron capture therapy (BNCT). BNCT employs intravenous administration of a boron compound, which is picked up more selectively by tumor cells than by normal brain tissue. The cyclotron delivers a single dose of radiation that triggers the release of high-energy particles from the boron to destroy nearby tumor cells. The cyclotron is available only in a very few locations, and there have been few trials to date.
Drugs Used With Radiation
Researchers are studying drugs that may be used along with radiation to increase the effectiveness of the treatment.
Radioprotectors. Drugs such as amifosistine (Ethyol) may protect healthy cells during radiation.
Radiosensitizers. Drugs such as fluorouracil (5-FU) and cisplatin (Platinol) may help make cancerous cells more sensitive to radiation.
Side Effects of Radiation
Common Side Effects. Side effects of radiotherapy may vary depending on the tumor type and radiation treatment. Side effects may include hair loss, fatigue, and nausea and vomiting. Skin irritation and sensitivity may develop in the areas being treated. To prevent further irritation, avoid scratching or rubbing, avoid direct sunlight and heating pads, and do not attempt to treat the symptoms yourself. (Ask your doctor or radiation therapist for advice.) Brain swelling (edema) is another common radiotherapy side effect, which can sometimes cause an increase in brain tumor symptoms. Edema can be treated with steroids.
Tissue Injury. Radiation necrosis (total destruction of nearby healthy tissue) occurs in about 25% of patients treated with intensive radiation. Radiation necrosis can cause brain swelling and reduction in mental functions. The condition is treated with steroids. If steroids prove ineffective, surgery may be required to remove the damaged tissue.
New Tumors. Radiation therapy for childhood cancer is the most important risk factor for developing new brain and spinal column tumors, according to a 2006 study. The risk appears greatest for children who received radiation therapy before age 5. Researchers found that the risk of second primary tumors increased in relation to the radiation dose used to treat the first cancer.
Stroke. Survivors of childhood brain tumors who were treated with high doses of cranial radiation (especially doses greater than 50Gy) may be at increased risk of having a stroke later in life. In a study of nearly 2,000 brain tumor survivors, the average length of time from cancer diagnosis to stroke was 14 years.
Chemotherapy
Chemotherapy involves the use of drugs to kill or alter cancer cells. Chemotherapy is not an effective initial treatment for low-grade brain tumors, mostly because standard drugs cannot pass through the blood-brain barrier, the functional system that protects the brain by preventing certain molecules from reaching the central nervous system. In addition, not all types of brain tumors respond to chemotherapy. In general, chemotherapy for brain tumors is usually administered following surgery or radiation therapy.
The type of drug determines how it is administered. "Systemic delivery" drugs, which pass to the brain from the bloodstream, may be given by mouth, injected into a vein through an IV, or injected into an artery or a muscle. "Local delivery" drugs are placed within or around the brain tumor.
Scientists are working on several approaches to overcome the blood-brain barrier. Newer delivery methods include:
- Interstitial chemotherapy uses disc-shaped polymer wafers (known as Gliadel wafers) soaked with carmustine, the standard chemotherapeutic drug for brain cancer. The surgeon implants the wafer directly into the surgical cavity after a tumor is removed.
- Intrathecal chemotherapy delivers chemotherapeutic drugs directly into the spinal fluid.
- Intraarterial chemotherapy delivers high-dose chemotherapy into arteries in the brain using tiny catheters. In one study, this approach was used within 2 weeks of radiotherapy in patients with high-grade astrocytomas, and the survival rates for glioblastoma multiforme tripled (20 months) compared to those who had chemotherapy and radiation at the same time.
- Convection-enhanced delivery (CED) involves placing catheters into the brain tumor or nearby brain tissue to deliver slowly and continuously a cancer drug over several days.
Chemotherapy Drugs and Regimens
Many different drugs, and drug combinations, are used for chemotherapy. Standard ones include:
Temozolomide (Temodar). Temozolomide, the first new drug approved for brain tumors in several decades, is taken by mouth as a pill. Temozolomide was first approved in 1999 for adult patients with anaplastic astrocytoma that did not respond to other treatments. In 2005, it was approved for use during and after radiation therapy for patients newly diagnosed with glioblastoma multiforme. The current first-line treatment for patients with glioblastoma is combined radiotherapy and temozolomide, followed by monthly doses of temozolomide after radiation treatment ends. A 2005 study, published in the New England Journal of Medicine, reported that adults with newly diagnosed glioblastoma who received temozolomide during and after radiation therapy had a higher rate of 2-year survival than patients who received radiation alone. A 2007 study in Neurology suggested that temozolomide works best for patients who are missing a particular gene (1p/19q). Temozolomides side effects are relatively minor, but may include constipation, nausea and vomiting, fatigue, and headache.
Carmustine (BCNU, BiCNU). Carmustine is used to treat many types of brain tumors, including glioblastoma, medulloblastoma, and astrocytoma. Carmustine is usually administered into the vein by IV. It can also be delivered through a wafer implant (Gliadel), which is surgically placed into the brain cavity after tumor removal. If carmustine is administered intravenously, side effects may include nausea and vomiting, fatigue, respiratory problems, and lung scarring (pulmonary fibrosis). Intravenous carmustine may cause bone marrow impairment, which results in decreased production of blood cells (a condition called myelosuppression). If carmustine is delivered through a wafer, side effects may include seizures, brain swelling, and infection within the brain cavity.
PCV Drug Regimen. PCV is an abbreviation for a chemotherapy regimen that combines procarbazine (Matulane), lomustine (CCNU), and vincristine (Oncovin). PCV is commonly used to treat oligodendrogliomas and oligoastrocytomas. The drugs may also be used alone or in other combinations. Procarbazine and lomustine are taken by mouth. Vincristine is given by either injection or IV. These drugs can cause significant side effects, including a drop in blood cell counts, nausea and vomiting, constipation, fatigue, and mouth sores. Procarbazine can cause high blood pressure when taken with foods high in tyramine. Patients should avoid foods such as beer, red wine, cheese, chocolate, processed meat, yogurt, and certain fruits and vegetables.
Platinum-Based Drugs. Cisplatin (Platinol) and carboplatin (Paraplatin) are standard cancer drugs that are sometimes used to treat glioma, medulloblastoma, and other types of brain tumors. These drugs are delivered by IV. In addition to nausea and vomiting, carboplatin can cause hair loss, and cisplatin can cause muscle weakness.
Investigational Drug Treatments
Patients with brain tumors, especially tumors that are in advanced stages, should consider enrolling in clinical trials. Many clinical trials are conducted through academic medical centers. Some promising areas of drug research include:
Other Chemotherapy Drugs. Researchers are investigating whether drugs used to treat other types of cancer may have benefits for brain tumors. These drugs include tamoxifen (Nolvadex) and paclitaxel (Taxol), which are used to treat breast cancer; topotecan (Hycamtin), which is used to treat ovarian and lung cancers; and vorinostat (Zolinza), which is approved for treatment of cutaneous T-cell lymphoma. Research presented at the 2007 meeting of the American Society of Clinical Oncology indicated that vorinostat may help patients with glioblastoma multiforme. Irinotecan (Campath) is another cancer drug that is being studied in combination treatment.
Molecular Targeted Therapy Drugs. One of the most promising developments in cancer treatment research has been the emergence of so-called "targeted therapies." Traditional chemotherapy drugs can be effective, but because they do not distinguish between healthy and cancerous cells their generalized toxicity can cause severe side effects. Targeted therapies work on a molecular level by blocking specific mechanisms associated with cancer cell growth and division. Because they selectively target cancerous cells, they may induce less severe side effects. In addition, these drugs hold the promise of creating options for more individualized cancer treatment based on a patient's genotypes.
Promising targeted therapies for brain tumors include:
- Anti-angiogenesis drugs block molecules involved with the growth of blood vessels that feed the tumor (a process called "angiogenesis," which is particularly important in the growth of glioblastomas.) These drugs starve tumors of vital nutrients and oxygen. Bevacizumab (Avastin) is being studied in combination with irinotecan for treatment of recurrent malignant gliomas. Bevacizumab targets vascular endothelial growth factor (VEGF), a specific angiogenesis growth factor. Cediranib (Recentin, AZD2171) is another VEGF inhibitor. In 2007 clinical trials, cediranib appeared to help make recurrent glioblastomas more responsive to chemotherapy and radiation treatment.
- Tyrosine kinase inhibitor drugs block proteins involved in tumor cell growth and production. Drugs that specifically target epidermal growth factor receptors (EGFR) are a type of tyrosine kinase inhibitor of special interest in brain tumor research. These drugs include erlotinib (Tarceva), imatinib (Gleevac), and gefitinib (Iressa).
- Farnesyl protein transferase inhibitors, such as tipifarnib (Zarnestra) and lonafarnib (Sarasar), are drugs that target a protein involved in the functioning of the cancer-causing Ras protein. Lonafarnib is being studied in combination with temozolomide, and tipifarnib in combination with radiation therapy.
- MTOR inhibitors target other enzymes involved in cell growth and replication. Everolimus (RAD-001) is being studied for glioblastoma multiforme and astrocytoma. Everolimus is related to rapamycin (Siroliumus) and tacrolimus (Prograf), which are also being investigated for brain tumor treatment. These drugs are commonly used to suppress the immune system to prevent rejection after organ transplantation.
Other Treatments
Researchers are testing several drugs that target specific mechanisms associated with brain cancer. Combinations of some of these drugs, with or without standard chemotherapy and radiotherapy, may prove to be more effective than the use of any one treatment. It should be noted that none of these drugs at this time are producing cures, although some are improving survival.
Immunotherapy
Immunotherapy aims at using modalities that boost the patient's own immune system's ability to seek out and destroy cancerous cells.
Radioimmunotherapy with Monoclonal Antibodies. Radioimmunotherapy is showing special promise as a treatment approach to brain tumors. It typically uses monoclonal antibodies (MAbs), genetically engineered drugs designed to work against a specific target. MAbs are bound with radioactive substances and delivered directly into the brain and sometimes into the tumor. The MAbs are specifically designed to lock with the surface of certain cells in the tumor. Once they do so, the radioactive substances destroy the cell. The approach is essentially mini-radiation therapy without the damage or severe side effects of standard radiation treatments. Numerous different radioimmunotherapies are being investigated, and trials of some are reporting improved survival rates in high-grade gliomas. Some doctors believe this approach could prove to be the most effective therapy against these cancers.
Interleukins. Interleukins are natural proteins created by the immune system. Certain tumor cells carry receptors for specific interleukins, which are being investigated for a possible therapeutic role. For example, some drugs combine an interleukin with a drug that is toxic to cancer cells. The interleukin locks onto the receptor on the cancer cell, and the toxic chemical enters the tumor with the intent to kill it. Some interleukins are also being investigated alone for their own tumor-cell killing properties.
Tumor Vaccines. Tumor vaccines are being created, in which tumor cells are removed from the patient and inactivated. When the tumor cells are transferred back to the patient, they are harmless but can elicit a powerful immunologic response against the tumor. Vitespan (Oncophage) is a tumor vaccine that is showing promise against recurrent high-grade glioma, according to preliminary results from early trials presented at the 2007 annual meeting of the American Association of Neurological Surgeons.
Cell Growth and Angiogenesis Inhibitors
Much research is focusing on drugs that block small molecules involved with the growth of blood vessels that feed the tumor (a process called angiogenesis). Such drugs, when effective, would starve tumors of vital nutrients and oxygen. Angiogenesis is particularly important in the growth of glioblastomas, the most malignant brain tumors. Of particular promise are drugs that inhibit enzymes called tyrosine kinase, farnesyl protein transferase, and matrix metalloproteinase, which play critical roles in angiogenesis.
Farnesyl Protein Transferase Inhibitors. Farnesyl protein transferase inhibitors, such as tipifarnib, also called R115777 (Zarnestra) and lonafarnib (Sarasar), are drugs in a new class that block a mutated gene called the Ras gene, which is responsible for about 30% of cancers. Lonafarnib is in early trials in combination with temozolomide. Tipifarnib is also currently in early trials and may prove to be effective.
Tyrosine Kinase Inhibitors. Drugs that target growth factor receptors, such as tyrosine kinase, interfere with the pathway leading to angiogenesis. Some tyrosine kinase inhibitors -- including erlotinib (Tarceva), imatinib (Gleevac), gefitinib (Iressa), and others -- are being investigated in early trials for brain tumor treatment. Side effects include rash, diarrhea, nausea and vomiting. Some of these drugs may reduce white blood cell count or cause liver damage. Researchers are trying to identify biomarkers that could help predict which patients would best respond to tyrosine kinase inhibitor therapy.
Matrix metalloproteinase Inhibitors. Matrix metalloproteinase is an important enzyme in angiogenesis. Inhibitors of these enzymes, including marimastat, metastat, and prinomastat, are in early trials. Marimastat has been studied and has shown some benefits in early trials for patients with recurrent glioblastoma and anaplastic gliomas, particularly in combination with temozolomide.
Phophoinositide 3-Kinse (Pi3K) Inhibitors. Rapamycin and its analog (CCI-779) inhibit Pi3K, an enzyme involved in cell growth. Early trials using CCI-779 are underway. (Another rapamycin analog, everolimus, has different effects but is also being studied for its actions in inhibiting cell growth.)
Other Drugs that Block Angiogenesis. Thalidomide was one of the first drugs used to inhibit angiogenesis and has undergone several trials. There is some evidence that it may work more effectively for metastasized brain tumors than primary tumors. Other drugs in early trials with various effects on tumor growth include suramin, cilengitide, semaxanib, PTK787, and atrasentan.
Other Investigative Drugs
Retinoids. Retinoids are vitamin A derivatives and act as differentiating drugs in cancer treatments. That is, they can convert immature, dividing tumor cells into mature cells, stopping tumor growth. Studies suggest that they have little benefits as single drugs. Combination with radiotherapy and other drugs may hold promise.
Inactivated Viruses. Investigators are finding that certain genetically inactivated viruses, such as the poliovirus or herpes virus, may prove to be valuable fighters of brain cancers. Such viruses can enter cells and destroy them but do not pose any danger for infection. For example, one specially designed herpes virus targets the enzyme thymidine kinase (an enzyme that promotes tumor growth). Some researchers believe that a combination of this virus with retinoids may be effective with few serious side effects. Other viruses are being investigated. A drug based on this model is years away, however.
Immunotoxins. Drugs called immunotoxins use natural toxins to kill malignant brain cells.
Drugs that use diphtheria toxins, including TransMID-107R and DAB(389)EGF), are the first immunotoxins to show some promise. Clinical trials are investigating them for gliomas and metastatic brain cancers. Other toxins under investigation include irofulven (a mushroom toxin) and chlorotoxin (a substance derived from scorpions).
Taurolidine. Taurolidine is a unique drug that prevents tumor formation and growth in animals. An early clinical trial in patients with high-grade gliomas is under way.
Protein-Blocking Drug. Another development is the discovery of a protein called BEHAB (Brain-Enriched Hyaluronan Binding Protein). BEHAB is produced only by invasive glioma tumor cells, not by normal brain tissue or noninvasive tumor cells. Breakdown of BEHAB releases a substance called HABD (hyaluronan-binding domain), which appears to give glioma cells the ability to invade other areas of the brain. Both BEHAB and HABD represent potential targets for new therapies.
Transplantation Procedures and High-Dose Chemotherapy
Chemotherapy destroys not only cancer cells but also healthy cells, including special blood cells in the bone marrow called stem cells. Stem cells are immature cells from which all blood cells develop. Transplantation procedures using bone marrow or stem cells allow high-dose chemotherapy to be administered while protecting blood cells. The procedures are being tested for patients with recurrent brain tumors, such as medulloblastoma, primitive neuroectodermal tumors, and germ cell tumors. A 2003 study reported long-term survival in some patients who underwent this procedure
Photodynamic Therapy
Photodynamic therapy uses a special drug (Photofrin) that is absorbed by the tumor and causes the cancer cells to become fluorescent when a laser is directed at them. It is being investigated in trials in combination with other treatments. A 2003 study reported encouraging results, notably in patients with recurring glioblastoma multiforme. In the study, more than half of these patients survived for at least a year.
Treatment of Complications
Hydrocephalus
Some tumors, particularly medulloblastomas, interfere with the flow of cerebrospinal fluid and cause hydrocephalus (accumulation of fluid in the skull). This causes a build-up fluid in the ventricles (the cavities) in the brain. Symptoms include nausea and vomiting, severe headaches, lethargy, difficulty staying awake, seizures, visual impairment, irritability, and tiredness.

Corticosteroids (commonly called steroids) such as dexamethasone (Decadron), prednisolone, and prednisone are used to treat hydrocephalus. Side effects include high blood pressure, mood swings, increased risk of infection, stronger appetite, facial swelling, and fluid retention.
Human corticotropin-releasing factor (hCRF), a naturally occurring neurohormone, appears to possess substantial anti-swelling properties and thus has been proposed as an alternative to corticosteroids in brain edema, with potentially fewer side effects. A hCRF drug called Xerecept is currently in clinical trials.
A shunt procedure may be performed to drain fluid. Shunts are flexible tubes used to reroute and drain the fluid.
Seizures
Seizures are common in brain tumor cases, with younger patients having higher risks than older ones. Anti-epileptic medications, such as carbamazepine or phenobarbital, may treat seizures and are helpful in preventing recurrence. These drugs are not useful in preventing a first seizure, however, and they should not be used routinely to treat patients with newly diagnosed brain tumors. Anti-seizure medications should be used only for patients who are experiencing seizures. Despite these guidelines, a 2005 study in the Journal of the American Medical Association reported that nearly 90% of patients with newly diagnosed malignant glioma are treated with anti-epileptic drugs, although only 32% of the patients actually have seizures. Anti-seizure medications can interact with some of the chemotherapies used to treat brain cancers, including paclitaxel, irinotecan, interferon, and retinoic acid. Patients should discuss these interactions with their doctors.
Depression
Antidepressants are very useful for treating the emotional side effects of this disease. However, according to a 2005 Journal of the American Medical Association study, only 8% of patients with malignant gliomas receive antidepressant medication even though over 90% report depressive symptoms. Support groups can also have great benefit for both patients and families.
Resources
- www.abta.org -- American Brain Tumor Association
- www.cbtf.org -- Children's Brain Tumor Foundation
- www.virtualtrials.com -- Musella Foundation for Brain Tumor Research and Information
- www.braintumor.org -- National Brain Tumor Foundation
- www.neurosurgery.org -- American Association of Neurologic Surgeons
- www.cancer.org -- American Cancer Society
- www.cancer.gov -- National Cancer Institute
- www.asco.org -- American Society for Clinical Oncology
- www.cancer.gov/clinicaltrials -- Find clinical trials
- www.radiologyinfo.org -- RadiologyInfo
- www.plwc.org -- People Living with CAncer
References
Bowers DC, Liu Y, Leisenring W, McNeil E, Stovall M, Gurney JG, et al. Late-occurring stroke among long-term survivors of childhood leukemia and brain tumors: a report from the Childhood Cancer Survivor Study. J Clin Oncol. 2006 Nov 20;24(33):5277-82. Epub 2006 Nov 6.
Dunlap SM, Celestino J, Wang H, Jiang R, Holland EC, Fuller GN, et al. Insulin-like growth factor binding protein 2 promotes glioma development and progression. Proc Natl Acad Sci U S A. 2007 Jul 10;104(28):11736-41. Epub 2007 Jul 2.
Flint-Richter P, Sadetzki S. Genetic predisposition for the development of radiation-associated meningioma: an epidemiological study. Lancet Oncol. 2007 May;8(5):403-10.
Kaloshi G, Benouaich-Amiel A, Diakite F, Taillibert S, Lejeune J, Laigle-Donadey F, et al. Temozolomide for low-grade gliomas: predictive impact of 1p/19q loss on response and outcome. Neurology. 2007 May 22;68(21):1831-6.
Keime-Guibert F, Chinot O, Taillandier L, Cartalat-Carel S, Frenay M, Kantor G, et al. Radiotherapy for glioblastoma in the elderly. N Engl J Med. 2007 Apr 12;356(15):1527-35.
Neglia JP, Robison LL, Stovall M, Liu Y, Packer RJ, Hammond S, et al. New primary neoplasms of the central nervous system in survivors of childhood cancer: a report from the Childhood Cancer Survivor Study. J Natl Cancer Inst. 2006 Nov 1;98(21):1528-37.
Sharma MK, Mansur DB, Reifenberger G, Perry A, Leonard JR, Aldape KD, et al. Distinct genetic signatures among pilocytic astrocytomas relate to their brain region origin. Cancer Res. 2007 Feb 1;67(3):890-900.
Vredenburgh JJ, Desjardins A, Herndon JE 2nd, Dowell JM, Reardon DA, Quinn JA,et al. Phase II trial of bevacizumab and irinotecan in recurrent malignant glioma. Clin Cancer Res. 2007 Feb 15;13(4):1253-9.
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.
















