What are Brain and Spinal Cord Tumors?
Brain and spinal cord tumors are found in the tissue inside the skull or the bony spinal column, which makes up the central nervous system (CNS). A tumor is a mass of cells that forms a new growth or is present at birth (congenital). Tumors occur when genes that regulate cell growth become damaged or mutated, allowing cells to grow and divide out of control. Tumors can form anywhere in the body.
Depending on its type, a growing tumor can kill healthy cells or disrupt their function. It can move or press on sensitive tissue and block the flow of blood and other fluid, causing pain and inflammation. A tumor can also block the normal flow of electricity in the brain or nerve signaling to and from the brain. Some tumors cause no trouble at all.
There are more than 120 types of brain and spinal cord tumors. Some are named by the type of normal cell they most closely resemble (such as glioma) or location (such as meningioma, which form in the lining of the brain and spinal cord). See the Appendix at the end of this guide for a listing of some CNS tumors and tumor-related conditions and the Glossary for specific terms and their meanings.
The following overview explains how the CNS works and what happens when a tumor is present.
Overview of the brain and spinal cord
The brain has three major parts:
- brain stem—This lowest part of the brain (above the neck) connects to the spinal cord and relays information between the brain and the body using bundles of long nerves. It controls basic life-sustaining functions, including blood pressure, heartbeat, breathing, consciousness, swallowing, and body temperature.
- cerebrum—This largest and outermost part of the brain processes information from our senses to tell the body how to respond. It controls functions including movement, touch, judgment, learning, speech, emotions, and thinking.
- cerebellum—Located at the lower rear of the brain, above the brain stem, the cerebellum controls balance, helps maintain equilibrium, and coordinates such complex muscle movements as walking and talking.
The brain’s two halves, or hemispheres, use nerve cells (neurons) to speak with each other. Each side of the cerebrum controls movement and function on the other side of the body. In addition, each hemisphere has four sections, called lobes, which handle different neurological functions.
The frontal lobes manage voluntary movement, such as writing, and let us set and prioritize goals. A frontal lobe tumor can cause changes in personality, intellect, reasoning, and behavior; affect coordination and walking, and cause speech loss. The temporal lobes are linked to perception, memory, and understanding sounds and words. A tumor here might cause speech and hearing problems, blackouts, seizures, or sensations such as a feeling of fear. The parietal lobes let us simultaneously receive and understand sensations such as pressure and pain. A parietal lobe tumor might cause difficulty understanding or speaking words, problems with coordination, seizures, and numbness or weakness on one side of the body. The occipital lobes receive and process light and visual images, and detect motion. An occipital lobe tumor can affect the field of vision, usually on one side of the view, and how we understand written words.
Three layers of protective tissue (called the meninges) cover the brain—the thick dura mater (outer layer), the arachnoid (middle), and the pia mater (innermost to the brain).
Brain tumors in infants and adults tend to be located in the cerebrum. Brain tumors in children ages 1-12 years are more commonly found in the cerebellum.
The spinal cord—an extension of the brain—lies protected inside the bony spinal column. It contains bundles of nerves that carry messages between the brain and other parts of the body, such as instructions from the brain to move an arm or information from the skin that signals pain.
A tumor that forms on or near the spinal cord can disrupt communication between the brain and the nerves or restrict the cord’s supply of blood. Because the spinal column is narrow, a tumor here—unlike a brain tumor—can cause symptoms on both sides of the body at the same time.
Most spinal cord tumors form below the neck. Symptoms generally strike body areas at the same level or at a level below that of the tumor. For example, a tumor midway along the spinal cord (in the thoracic spine) can cause pain that spreads over the chest and gets worse when the individual coughs, sneezes, or lies down. A tumor that grows in the cervical spine can cause pain that seems to come from the neck or arms, and a tumor that grows in the lower, lumbar spine can trigger back or leg pain.
The three major groups of spinal cord tumor describe where they are found. Extradural tumors grow between the inner surface of the spinal canal and the tough dura mater. Tumors inside the dura (intradural tumors) are further divided into those outside the spinal cord (extramedullary tumors) and those inside the spinal cord (intramedullary tumors). Other descriptors for spinal cord tumors are intrinsic, meaning the tumor forms inside the spinal cord; and extrinsic, where the tumor forms outside of and presses on the cord as it grows.
CNS Tumor FAQS
What are benign and malignant tumors?
No matter where they are located in the body, tumors are classified as benign or malignant.
Benign tumors are slow growing, non-cancerous cell masses that have a defined edge and do not spread to other parts of the body. Cells in the tumor are similar to normal cells. Often these tumors can be removed surgically and usually do not recur.
Malignant, or cancerous, tumors have cells that look different from normal cells. They can quickly invade surrounding tissue and often have edges that are hard to define, which makes it difficult to remove the entire tumor surgically.
What are primary and metastatic tumors?
Primary tumors of the CNS are growths that begin in the brain or spinal cord. They can be either malignant or benign and are identified by the types of cells they contain, their location, or both. Most primary CNS tumors occur in adults.
Metastatic, or secondary, tumors in the CNS are caused by cancer cells that break away from the primary tumor that developed in a non-CNS part of the body. These tumors are named after the type of cancer that causes them. Metastastic tumors (also called metastases) to the brain occur in about one-fourth of all cancers that develop in other parts of the body, such as cancer of the lung, breast, or kidneys; or melanoma, a form of skin cancer. They are more common than primary tumors and occur more often in adults than in children.
Metastatic spine tumors usually form within the bony covering of the spinal column but may also invade the spinal canal from the chest or abdomen.
While cancers elsewhere in the body can easily cause tumors inside the brain and spinal cord, CNS tumors rarely spread outside the nervous system.
What causes CNS tumors?
Researchers really don’t know why primary brain and spinal cord tumors develop. Possible causes under investigation include viruses, defective genes, exposure to certain chemicals and other hazardous materials, and immune system disorders. Although smoking, alcohol consumption, and certain dietary habits are associated with some types of cancers, they have not been linked to primary CNS tumors.
In a small number of individuals, CNS tumors may result from specific genetic diseases, such as neurofibromatosis and tuberous sclerosis, or exposure to radiation. It is currently unclear if non-ionizing radiation (radio waves) from mobile phone use increases the risk of developing a brain tumor.1
Brain and spinal cord tumors are not contagious or, at this time, preventable.
Who is at risk?
Anyone can develop a primary CNS tumor, although the risk is very small. Having one or more of the known risk factors does not guarantee that someone will develop a tumor. Brain tumors occur more often in males than in females and are most common in middle-aged to older persons. They also tend to occur more often in children under age 9 than in other children, and some tumors tend to run in families. Most brain tumors in children are primary tumors.
Other risk factors for developing a primary CNS tumor include race (Caucasians are more likely to develop a CNS tumor than other races) and occupation. Workers in jobs that require repeated contact with ionizing radiation or certain chemicals, including those used to manufacture building supplies or plastics and textiles, have a greater chance of developing a brain tumor.
How many people have these tumors?
More than 359,000 persons in the United States are estimated to be living with a diagnosis of primary brain or central nervous system tumor.2 More than 195,000 Americans are diagnosed with a brain tumor each year.3 Brain tumors are the most common form of solid tumor in children.
Spinal cord tumors are less common than brain tumors. Although they affect people of all ages, spinal cord tumors are most common in young and middle-aged adults. Nearly 3,200 central nervous system tumors are diagnosed each year in children under age 20.4
How are tumors graded?
The generally accepted scale for grading CNS tumors was approved by the World Health Organization in 1993. Grading is based on the tumor’s cellular makeup and location. Tumors may also be classified as low-grade (slowly growing) or high-grade (rapidly growing). Some tumors change grades as they progress, usually to a higher grade, and can become a different type of tumor. The tumor is graded by a pathologist following a biopsy or during surgery.
Grade I tumors grow slowly and generally do not spread to other parts of the brain. It is often possible to surgically remove an entire grade I benign tumor, but this type of tumor may be monitored periodically, without further treatment.
Grade II tumors also grow slowly, sometimes into surrounding tissue, and can become a higher-grade tumor. Treatment varies according to tumor location and may require chemotherapy, radiation, or surgery followed by close observation.
Grade III tumors are malignant and can spread quickly into other CNS tissue. Tumor cells will look different than those in surrounding tissue. Aggressive treatment, often using a combination of chemotherapy, radiation, and/or surgery, is required.
Grade IV tumors invade nearby tissue very quickly and are difficult to treat. The cancerous tissue will look very different from surrounding tissue. Aggressive treatment is required.
What are the possible symptoms?
Brain and spinal cord tumors cause many diverse symptoms, which can make detection tricky. Symptoms depend on tumor type, location, size, and rate of growth. Certain symptoms are quite specific because they result from damage to particular areas of the brain. Symptoms generally develop slowly and worsen as the tumor grows.
The most obvious sign of a brain tumor in infants is a rapidly widening head or bulging crown.
Common symptoms of a brain tumor in adults include headaches, seizures, problems with balance or coordination, loss of muscle control, hydrocephalus, and changes in personality or behavior.
Headaches are the most common symptom of a brain tumor. Headaches may progressively worsen, become more frequent or constant, and recur, often at irregular intervals. Headache pain may worsen when coughing, changing posture, or straining and may be severe upon waking.
Seizures can occur, with symptoms that may include convulsions, loss of consciousness, or loss of bladder control. Seizures that first start in adulthood (in someone who has not been in an accident or who had an illness that causes seizures) are a key warning sign of brain tumors.
Nausea and vomiting may be more severe in the morning and may accompany headaches.
Vision or hearing problems can include blurred or double vision, partial or total loss of vision or hearing, ringing or buzzing sounds, and abnormal eye movements.
Personality, behavior, and cognitive changes can include psychotic episodes and problems with speech, language, thinking, and memory.
Motor problems can include weakness or paralysis, lack of coordination, or gradual loss of sensation or movement in an arm or leg. A sudden, marked change in handwriting may be a sign of a tumor.
Balance problems can include dizziness, trouble with walking, clumsiness, or loss of the normal control of equilibrium.
Hydrocephalus and increased intracranial pressure are caused when a tumor blocks the flow of the cerebrospinal fluid (CSF) that surrounds the brain and spinal cord. Symptoms may include headaches, nausea, and vomiting.
Other symptoms may include endocrine disorders or abnormal hormonal regulation, difficulty swallowing, facial paralysis and sagging eyelid, fatigue, weakened sense of smell, or disrupted sleep and sleep pattern changes.
Common symptoms of a spinal cord tumor include pain, numbness or sensory changes, and motor problems and loss of muscle control.
Pain can feel as if it is coming from various parts of the body. Back pain may extend to the hips, legs, feet, and arms. This pain is often constant and may be severe. It is often progressive and can have a burning or aching quality.
Numbness or sensory changes can include decreased skin sensitivity to temperature and progressive numbness or a loss of sensation, particularly in the legs.
Motor problems and loss of muscle control can include muscle weakness, spasticity (in which the muscles stay stiffly contracted), and impaired bladder and/or bowel control. If untreated, symptoms may worsen to include muscle wasting, decreased muscle strength, an abnormal walking rhythm known as ataxia, and paralysis.
Symptoms may spread over various parts of the body when one or more tumors extend over several sections of the spinal cord.
How are CNS tumors diagnosed?
A doctor, usually a neurologist, oncologist, or neuro-oncologist, can confirm a diagnosis of a brain or spinal cord tumor based on a patient’s symptoms, personal and family medical history, and results of a physical exam and specialized tests and techniques.
A neurological exam—the first test—assesses movement and sensory skills, hearing and speech, reflexes, vision, coordination and balance, mental status, and changes in mood or behavior, among other abilities. Some tests require a specialist to perform and analyze results.
The doctor will order one or more imaging techniques that show extremely detailed views of body structures, including tissues, organs, bones, and nerves. If there is a tumor, diagnostic imaging will confirm the diagnosis and help doctors determine the tumor’s type, detect swelling and other associated conditions, and, over time, check the results of treatment.
See the NINDS publication, “Neurological Diagnostic Tests and Procedures,” for a more complete description of the following tests:
Computed Tomography (CT) uses x-rays and a computer to produce fast, detailed cross-sectional images or “slices” of organs, bones, and tissues, including a tumor. It is also good for detecting the buildup of calcium, which causes tissue to harden and can develop into a tumor.
Magnetic Resonance Imaging (MRI) uses a computer, radio waves, and a strong magnetic field to produce two-dimensional slices or a detailed three-dimensional model of tissue being scanned. MRI takes longer to perform than does a CT but is more sensitive and gives better pictures of tumors located near bone.
Both CT and MRI scans for tumor are usually performed before and after administration of a “contrast” agent (such as a dye) that is given into a vein. Many tumors become much brighter on the scan taken after the contrast is given.
Functional MRI (fMRI) creates images of areas of the brain with specific functions such as movement and language. It can assess brain damage from head injury or degenerative disorders, identify and monitor other neurological disorders such as stroke, and show the distance between specific brain functions and tumors in particular areas of the brain.
Magnetic Resonance Spectroscopy (MRS) gives doctors a chemical snapshot of tissues being studied. It uses the MRI scanner’s magnetic field and radio waves to measure and analyze the chemical make-up of the tissue sample.
Positron Emission Tomography (PET) provides computer-generated two- and three-dimensional scans of the brain’s chemical activity and cellular function. PET traces and measures the brain’s use of glucose (sugar, used by the brain for energy) that is attached to small amounts of radioactivity and injected into the bloodstream. Since malignant tissue uses more glucose than normal tissue, it usually shows up on the scan as brighter than surrounding tissue.
Single Photon Emission Computed Tomography (SPECT) studies blood flow to tissue. Certain tumors grow new blood vessels to increase their supply of blood and nutrients. A radioactive isotope is injected intravenously and traced as it travels into the skull. A sophisticated computer processes and stacks the data into a detailed three-dimensional image of activity within the brain.
Angiography (or arteriogram) can distinguish certain types of tumors that have a characteristic pattern of blood vessels and blood flow. A dye that deflects x-rays is injected into a major blood vessel and a series of x-rays is taken as the dye flows to the brain. In many situations angiography has been replaced by non-invasive tests such as CT and MRI.
Testing blood, urine, and other substances can provide clues about the tumor and monitor levels of therapeutic drugs.
Additional tests may include an electroencephalogram, or EEG, which monitors brain activity through the skull (tumors can disrupt the normal flow of brain wave activity and cause seizures); CSF analysis, in which a small amount of the cerebrospinal fluid is removed by a special needle and examined for abnormal cells or unusual levels of various compounds that suggest a brain or spinal cord tumor; and magnetoencephalography (MEG), which studies brain function by measuring the magnetic field generated by nerve cells in the brain. CSF fluid analysis should be performed with extreme caution on individuals with very large brain tumors.
Diagnosing the distinct type of brain tumor is often difficult. Individuals should consider asking their primary care physician or oncologist for a second opinion, particularly from a neuro-oncologist or neurosurgeon, as there may be new information available and some tumors can change grade or recur. Even a second opinion that confirms the original diagnosis can help people better prepare for their care and treatment.
How are brain and spinal cord tumors treated?
A specialized team of doctors advises and assists individuals throughout treatment and rehabilitation. These doctors may include:
A neurologist is a specialist in nervous system disorders.
An oncologist is a specialist in cancer.
A neuro-oncologist is a neurologist or oncologist who specializes in nervous system tumors.
A neuroradiologist is a doctor trained in reading diagnostic imaging results who specializes in the CNS.
A pathologist is a clinical physician who diagnoses diseases of tissues or cells using a variety of laboratory tests.
A neurosurgeon is a brain or spinal cord surgeon.
A radiation oncologist is a doctor who specializes in using radiation to treat individuals with cancer.
This team will recommend a treatment plan based on the tumor’s location, type, size and aggressiveness, as well as on the individual’s medical history, age, and general health.
Initial treatment for a CNS tumor may involve a variety of drugs, including anticonvulsants to treat seizures, pain medications, steroids or other anti-inflammatory drugs to reduce swelling and improve blood flow, antidepressants to treat anxiety or ease depression that might occur following a tumor diagnosis, and drugs to fight nausea caused by various treatments.
Malignant tumors require some form of treatment, while some small benign tumors may need only periodic monitoring. The three standard treatment options for malignant CNS tumors are neurosurgery, radiation therapy, and chemotherapy. Some patients may receive a combination of treatments.
Surgery is usually the first step in treating an accessible tumor—one that can be removed without unacceptable risk of neurological damage. Surgery is aimed at removing all or as much tumor as possible (called resecting or excising) and can often slow worsening of neurological function.
An inaccessible or inoperable tumor is one that cannot be removed surgically because of the risk of severe nervous system damage during the operation. These tumors are frequently located deep within the brain or near vital structures such as the brain stem.
A biopsy is sometimes performed to help doctors determine how to treat a tumor. A brain biopsy involves surgically removing a small part of the skull to sample the tumor tissue. Biopsies can sometimes be performed by a needle inserted through a small hole. A small piece of tissue remains in the hollow needle when it is removed from the body. A pathologist will stain and examine the tissue for certain changes that signal cancer and grade it to reflect the degree of malignancy.
If the sample is cancerous, the surgeons will remove as much of the tumor as possible. For some primary brain tumors it is not possible to surgically remove all malignant cells. Malignant brain tumors commonly recur from cells that have spread from the original tumor mass into the surrounding brain tissue. In contrast, many benign tumors and secondary metastatic tumors can be completely removed surgically.
In some cases, a surgeon may need to insert a shunt into the skull to drain any dangerous buildup of CSF caused by the tumor. A shunt is a flexible plastic tube that is used to divert the flow of CSF from the central nervous system to another part of the body, where it can be absorbed as part of the normal circulatory process.
Fortunately, research has led to advances in neurosurgery that make it possible for doctors to completely remove many tumors that were previously thought to be inoperable. These new techniques and tools let neurosurgeons operate within the tight, vulnerable confines of the CNS. Some tools used in the operating room include a surgical microscope, the endoscope (a small viewing tube attached to a video camera), and miniature precision instruments that allow surgery to be performed through a small incision in the brain or spine.
Intraoperative MRI uses a special type of MRI to provide a real-time evaluation of the surgery. Constantly updated images that are provided during surgery let doctors see how much tumor material has been removed. Intraoperative MRI can also help doctors choose the best surgical approaches and monitor any complications during surgery.
Navigation equipment used in computer-guided, or stereotactic, neurosurgery gives doctors a precise, three-dimensional map of an individual’s spine or brain as the operation progresses. A computer uses pre-operative diagnostic images of the individual to reduce the risk of damage to surrounding tissue.
Intraoperative nerve monitoring tests such as evoked potentials use real-time recordings of nerve cell activity to determine the role of specific nerves and monitor brain activity as the surgery progresses. Small electrodes are used to stimulate a nerve and measure its electrical response (or evoked potential). Some surgeries may be done while the individual is awake under monitored anesthesia care, rather than under general anesthesia. This allows doctors to monitor the individual’s speech and motor functions as a tumor is being removed.
A possible side effect of surgery is swelling around the site of the tumor, and can be treated with steroids. Bleeding into the tumor site or infection are other serious risks of brain surgery.
In the cae of metastatic tumors, doctors usually treat the original cancer. However, if there are only one or two metastases to the brain or if a metastatic tumor causes serious disability or pain, doctors may recommend surgery—even if the original cancer has not been controlled.
Surgery may be the beginning and end of your treatment if the biopsy shows a benign tumor. If the tumor is malignant, doctors often recommend additional treatment, including radiation and chemotherapy, or one of several experimental treatments.
Radiation therapy usually involves repeated doses of x-rays or other forms of radiation to kill cancer cells or keep them from multiplying. When successful, this therapy shrinks the tumor mass but does not actually remove it. Radiation therapy can be used to treat surgically inaccessible tumors or tumor cells that may remain following surgery.
Depending on tumor type and stage, radiation treatment might be delivered externally, using focused beams of energy or charged particles that are directed at the tumor, or internally, using a surgically implanted device. The stronger the radiation, the deeper it can penetrate to the target site. Healthy cells may also be damaged by radiation therapy but most are able to repair themselves, while the damaged tumor cells cannot.
A radiation oncologist will explain the therapy and how much radiation is needed. Treatment often begins a week after surgery and may continue for several weeks. Depending on tumor type and location, individuals may be able to receive a modified form of therapy to lessen damage to healthy cells and improve the overall treatment.
Externally-delivered radiation therapy poses no risk of radioactivity to the patient or family and friends. Types of external radiation therapy include:
Whole brain radiation is generally used to shrink multiple cancerous tumors, rather than to target individual tumors. It may be given as the sole form of treatment or in advance of other forms of radiation therapy and microsurgery. Whole brain radiation is generally used for metastatic tumors and rarely for primary tumors.
Conventional external beam radiation aims a uniform dose of high-energy radiation at the tumor and surrounding tissue from outside the body. It is used to treat large tumors or those that may have spread into surrounding tissue.
Three-dimensional conformal radiotherapy (3D-CRT) uses diagnostic imaging to prepare an accurate, computer-generated three-dimensional image of the tumor and surrounding tissue. The computer then coordinates and sends multiple beams of radiation to the tumor’s exact shape, sparing nearby organs and surrounding tissue.
Intensity modulated radiation therapy (IMRT) is similar to 3D-CRT but varies the intensity of the hundreds of individual radiation beams to deliver more precise doses to the tumor or to specific areas within it. IRMT can provide a highly effective dose of radiation to the tumor, with less exposure to surrounding tissue.
Hyperfractionation involves giving two or more smaller amounts of radiation a day instead of a larger, single dose. It can deliver more radiation to certain tumors and reduce damage to normal cells.
Radiosurgery is usually a one-time treatment involving a large amount of sharply focused radiation that is aimed at the brain tumor. Stereotactic radiosurgery uses computer imaging to direct precisely focused radiation into the tumor from multiple angles. It does not actually cut into the person but, like other forms of radiation therapy, harms a tumor cell’s ability to grow and divide. Stereotactic radiosurgery is commonly used to treat surgically inaccessible tumors. It also may be used at the end of conventional radiation treatment. Two common stereotactic radiosurgery procedures are:
- Linear-accelerated radiosurgery (LINAC) uses radar-like technology to prepare and fire a single beam of high-energy x-rays into the tumor. Also called high linear-energy transfer radiation, LINAC forms the beam to match the tumor’s shape, avoiding surrounding tissue. A special machine that rotates around the head then fires a uniform dose of radiation into the tumor.
- Gamma knife® radiosurgery focuses more than 200 beams of gamma radiation into one intersecting beam that is fired into the tumor. It also uses computer imaging to prepare a model of the tumor. This single treatment takes between one and four hours and is often recommended for inaccessible or hard to treat tumors.
Both procedures may be given on an outpatient basis but an overnight stay in the hospital is often recommended.
Proton beam therapy directs a beam of high-energy protons directly at the tumor site, leaving surrounding healthy tissue and organs intact. It is best used to treat tumors that are solid and have not spread to other parts of the body. Proton beam therapy can be used as a stand-alone treatment or in combination with chemotherapy or as follow-up to surgery.
Internal tumor radiation therapy, also called brachytherapy or interstitial radiation therapy, involves placing a small amount of radioactive material into or near the tumor (or its cavity, if the tumor has been surgically removed). In most cases, the radiation is inserted at the time of surgery or using imaging and a catheter. The radiation may be left in place for several days and, if more than one treatment is needed, the doctor may leave the catheter in place for a longer period.
Individuals may need to be hospitalized for a few days following this procedure as the radiation may extend outside their body and could possibly harm others. The radiation becomes less active each day until it is safe for individuals who have been treated to be around others.
Side effects of radiation therapy vary from person to person and are usually temporary. They typically begin about two weeks after treatment starts and may include fatigue, nausea, vomiting, reddened or sore skin in the area receiving treatment, headache, hearing loss, problems with sleep, and hair loss (although the hair usually grows back once the treatment has stopped). Radiation therapy in young children, particularly those children age three or younger, can cause problems with learning, processing information, thinking, and growing.
Chemotherapy uses powerful drugs to kill cancer cells or stop them from growing or dividing. These drugs are usually given by pill or injection and travel through the body to the brain, or can be inserted surgically using dissolvable wafers that have been soaked in a chemotherapeutic drug. These wafers slowly release a high concentrate of the drug to kill any remaining malignant cells. Chemotherapy may also be given to kill cancer cells in the spinal column.
Chemotherapy is given in cycles to more effectively harm cancer cells and give normal cells time to recover from any damage. The oncologist will base the treatment on the type of cancer, drug(s) to be used, the frequency of administration, and the number of cycles needed.
Individuals might receive chemotherapy to shrink the tumor before surgery (called neo-adjuvant therapy), in combination with radiation therapy, or after radiation treatment (called adjuvant therapy) to destroy any remaining cancer cells. Metronomic therapy involves giving continuous low-dose chemotherapy to block mechanisms that stimulate the growth of new blood vessels needed to feed the tumor. Chemotherapy is also used to treat CNS lymphoma and inaccessible tumors or tumors that do not respond to radiation therapy.
Not all tumors are vulnerable to the same anticancer drugs, so a person’s treatment may include a combination of drugs. Common CNS chemotherapeutics include temozolomide, carmustine (also called BCNU), lomustine, tamoxifen, carboplatin, methotrexate, procarbazine, and vincristine. Individuals should be sure to discuss all options with their medical team.
Side effects of chemotherapy may include hair loss, nausea, digestive problems, reduced bone marrow production, and fatigue. The treatment can also harm normal cells that are growing or dividing at the same time, but these cells usually recover and problems stop once the treatment has ended.
Alternative and complementary approaches may help tumor patients better cope with their diagnosis and treatment. Some of these therapies, however, may be harmful if used during or after cancer treatment and should be discussed with a doctor beforehand. Common approaches include nutritional and herbal supplements, vitamins, special diet, and mental or physical techniques to reduce stress.
What is the prognosis?
Each person is different. Prognosis depends greatly on prompt diagnosis and treatment, the individual’s age and general health, whether the tumor is malignant or benign, tumor size and location, tumor grade, and response to therapy. An individual whose entire tumor has been removed successfully may recover completely. Generally, prognosis is poorer in very young children and in older individuals. Rehabilitation and counseling can help patients and family members better cope with the disorder and improve quality of life.
Continued monitoring and long-term follow-up is advised as many tumors resist treatment and tend to recur.
Normal tissue and nerves that may have been damaged or traumatized by the tumor or its treatment will need time to heal. Some post-treatment symptoms will disappear over time. Physical therapy can help people regain motor skills, muscle strength, and balance. Some individuals may need to relearn how to swallow or speak if the brain’s cognitive areas have been affected. Occupational therapy can teach people new ways to perform tasks. Supportive care can help people manage any pain and other symptoms.
What Research is Being Done?
Scientists continue to investigate ways to better understand, diagnose, and treat CNS tumors. Several of today’s treatment regimens were experimental therapies only a decade ago. Current clinical studies of genetic risk factors, environmental causes, and molecular mechanisms of cancers may translate into tomorrow’s treatment of, or perhaps cure for, these tumors.
Much of this work is supported by the National Institutes of Health (NIH), through the collaborative efforts of its National Institute of Neurological Disorders and Stroke (NINDS) and National Cancer Institute (NCI), as well as other agencies within the Federal government, nonprofit groups, pharmaceutical companies, and private institutions. Some of this research is conducted through the collaborative neuroscience and cancer research community at the NIH or through research grants to academic centers throughout the United States.
The jointly sponsored NCI-NINDS Neuro-Oncology Branch coordinates research to develop and test the effectiveness and safety of novel therapies for people with CNS tumors. These experimental treatment options may include new drugs, combination therapy, gene therapy, biologic immuno-agents, surgery, and radiation. Information about these trials, and trials involving other disorders, can be accessed at the Federal government’s database of clinical trials,http://clinicaltrials.gov.
Part of this research involves creating a comprehensive public database of clinical, molecular, and genetic information on brain tumors to help researchers and clinicians identify and evaluate molecular targets in brain cancer. The joint NCI-NINDS Repository for Molecular Brain Neoplasia Data (REMBRANDT) will hold genetic and molecular analysis of samples from brain tumor patients in NCI-sponsored clinical trials in what is slated to become the largest clinical/genetic corollary study ever conducted on brain tumors. It will also store a wide array of molecular and genetic data regarding all types of brain tumors. Understanding the biology behind these tumors will provide clues to new therapeutic approaches.
Researchers are also developing mouse models that mimic human CNS cancers, which may speed discovery of potential treatments in humans.
Beyond their efforts to develop needed resources, scientists at the NIH and at universities across the US are are exploring a variety of approaches to treat CNS tumors. These experimental approaches include boosting the immune system to better fight tumor cells, developing therapies that target the tumor cell while sparing normal cells, making improvements in radiation therapy, disabling the tumor using genes attached to viruses, and defining biomarkers that may predict the response of a CNS tumor to a particular treatment.
Biological therapy involves enhancing the body’s overall immune response to recognize and fight cancer cells. The immune system is designed to attack foreign substances in the body; since cancer cells aren’t foreign, they usually do not generate much of an immune response. Researchers are using different methods to provoke a strong immune response to tumor cells. Such proteins as interleukin and interferon, both of which are immune system “messengers” called cytokines, and other substances can stimulate and restore the body’s natural response against proteins on the surfaces of cancer cells and thus slow tumor growth. Other therapy uses viruses, T-cells (a major component of immune system function), and other substances to increase immune response and target the tumor cells. Scientists are also experimenting with genetically altered T-cells from the patient’s own body, which are cultured with an antigen and injected directly into the brain following surgery. Biological therapies to fight CNS tumors include vaccines, gene therapy, antibody therapy, and tumor growth factors.
Antibodies are proteins that are normally produced by the body to ward off bacteria and viruses. Monoclonal antibodies are multiple copies of a single antibody that act as a homing device to fit one—and only one—type of antigen (a protein on the surface of the tumor cell that stimulates the immune system response). Scientists at the NINDS and elsewhere are linking these antibodies to immunotoxins that seek out tumor cells with a matching antigen, bind to these tumor cells, and deliver their toxin, with minimal damage to surrounding normal cells. Additional approaches include attaching a radioactive substance to the antibodies, which act as targeting agents to deliver radiation to the tumor cell.
Gene therapy (also called gene transfer) aims to deliver a suicide gene to the tumor cell. It can also be used to boost the immune system. A gene whose activity can be influenced to kill the cell is integrated into a virus that can cross the blood-brain barrier (an elaborate network of fine blood vessels and cells that filters the blood reaching the CNS) and travel to the tumor. Delivery methods under investigation include viruses and stem cells. Gene therapy may become an important add-on therapy for individuals who do not respond well to other treatments.
Scientists are testing the effectiveness of vaccine therapy for a variety of CNS tumors. Vaccine therapy strengthens the immune response by inserting an antigen that the body will attack. Some vaccines target a specific antigen, while others, using the whole tumor cell to make the vaccine, hope to target multiple antigens which the tumor may express. Research has shown the vaccine can be genetically engineered with tumor antigens and injected into the body to induce an immune response, which increases the attack on antigens expressed on the surface of the tumor cell. Experimental CNS tumor vaccines include those designed to stimulate an immune response to a particular protein or antigen, and dendritic cell vaccines (in which blood cells are taken from the body, processed in a laboratory and given back to the patient to break up the tumor cell outer protein into smaller pieces, which increases targeting by immune cells).
Findings from NIH-sponsored research on adult CNS tumor development and treatment suggest the immune system and, potentially, infection with the cytomegalovirus may play a critical role in certain tumor-type risk and prognosis. Repeated stimulation of the immune system to counter this herpes virus may serve as a tumor promotion factor. Scientists hope to identify immune factors and develop targeted immunotherapies for this disease.
Targeted therapy uses different molecules to reduce tumor gene expression and suppress uncontrolled growth by killing or reducing the production of tumor cells. Of particular interest to scientists is the development of tailored therapeutics—involving a combination of targeted agents—to treat tumors based on tehir genetic make-up. Specifically, molecularly targeted drugs seek out the molecular and cellular changes that convert normal cells into cancer. Many targeted cancer therapies are being tested in animals for use alone or in combination with other cancer treatments, such as chemotherapy. Researchers hope to discover tumor-specific cellular or molecular pathways that can be used to increase drug delivery and to find ways to identify patients who may benefit from combined therapy. Targeted therapies include oncogenes, growth factors, and molecules aimed at blocking gene activity.
Growth factors often govern normal cell growth. Growth factors are released from either the cell or the surrounding tissue. Cancer cells can either secrete these growth factors or respond to them, enabling them to divide out of control. A number of tumor growth factors have been identified, including those that trigger nerve tissue growth and stimulate blood vessels to grow (a process called angiogenesis). Researchers continue to identify and develop agents that can block these factors.
Anti-angiogenetic compounds block blood vessel growth and the flow of nutrients and oxygen to the tumor, and may also hamper cell signaling and stop tumor cells from spreading elsewhere in the body. Clinical trials have shown that anti-angiogenetics can improve the outcome for glioblastoma multiforme tumors that recur following initial treatment with radiation and chemotherapy. More than a dozen such compounds have been identified, including bevacizumab, interferon, and endostatin. Researchers are studying the combination of anti-angiogenics and radiation or chemotherapy in treating newly diagnosed brain tumors. Other research is testing angiogenic inhibitors that have had positive results in adults on children with primary CNS tumors and in patients with tumors that haven’t responded well to other tumor treatment.
Oncogenes are transformed genes that are involved in cell growth and cause normal cells to divide uncontrolled and become malignant, either through mutation or over-expression. Researchers have identified specific events that lead to this mutation and are developing diagnostic and therapeutic screening tools.
Certain enzymes that are involved in cell division or the copying of genetic information may be over-produced in cancer cells, causing gene mutations and uncontrolled cell growth. Several different types of kinase inhibitors—proteins that block growth-signaling enzymes without harming normal cells—have been identified and approved for cancer treatment. Scientists are testing protein-level kinase inhibitors to see of they make CNS tumors more sensitive to chemotherapy. Clinical trials for brain tumors are studying the safety and effectiveness of kinase inhibitors in children with CNS tumors and in other patients with recurring or hard to treat tumors.
Anti-sense oligonucleotide technology uses short fragments of nucleic acid molecules to block gene expression in specific cells and prevent tumor growth. Unlike gene therapy, anti-sense oligonucleotide technology does not replace or substitute genetic material but inhibits the expression of select targets. This technology (also known as RNA interference, siRNA, or shRNA) may help scientists to identify additional genes involved in tumor formation and improve drug delivery with fewer side effects.
Of particular interest are microRNAs (or miRNAs)—naturally occurring molecules that regulate gene expression and are involved in the formation and development of tumor stem cells. Researchers are using miRNAs to switch off tumor stem cell activity. Researchers are studying miRNAs as a possible diagnostic and therapeutic strategy for brain tumors and other forms of cancer.
Biomarkers are molecules or others substances in the blood or tissue that can be used to diagnose or monitor a particular disorder, among other functions. As cells become cancerous, they can release unique proteins and other molecules into the body which scientists use to speed diagnosis and treatment. Some CNS tumor biomarkers have been found, such as the epithelial growth factor receptor (EGRF) gene. Researchers continue to search for additional clinical biomarkers of CNS tumors, to better assess risk from environmental toxins and other possible causes, and monitor and predict the outcome of CNS tumor treatment. NINDS-funded research has recently shown that mutation analysis of EGFR can be used to predict which tumors are most likely to respond to a specific class of cancer-fighting drugs. Identifying biomarkers may also lead to the development of new models of disease and novel therapies for tumor treatment.
Radiation therapy research incluces testing several new anticancer drugs, either independently or in combination with other drugs. Researchers are also testing different drugs in combination with other therapies and are investigating combined therapies such as radiation and radiosurgery to effectively treat CNS tumors. Research areas being explored include tomotherapy, boron nuclear capture therapy, liquid radiation therapy, and the use of radiosensitizers.
Radiosensitizers are drugs that make rapidly dividing tumor tissue more vulnerable to radiation. Early studies using radiosensitizers produced mixed results. While some trials suggested these drugs may improve survival in certain patients, other trials were found to have little benefit. Scientists are now testing an experimental drug that increases the amount of oxygen that is released from the blood into the tissues, making cancer cells more responsive to radiation and chemotherapy. Studies show the lack of oxygen in a tumor can make radiation therapy less effective.
Tomotherapy combines CT scanning and intensity modulated radiation therapy to deliver small beams of high-dose radiation to the tumor while greatly reducing radiation exposure to surrounding tissue. Studies are examining the effectiveness of radiation delivery through tomotherapy and to see if long-term side effects of radiation therapy can be reduced.
Boron Neutron Capture Therapy (BNCT) is an experimental treatment that uses fission to kill tumor cells. An amino acid or other drug that carries boron is injected into the patient, where it collects more readily in tumor cells than in regular tissue. A beam of low-energy neutrons is directed at the tumor from outside the body, causing the boron atoms to split (called neutron capture) and send high amounts of energy into the cancerous cells. Radiation damage to surrounding cells is extremely small. BNCT is being tested as a post-surgery treatment for patients with certain head and neck tumors. If successful, BNCT could someday be used to treat children with brain tumors.
Liquid radiation therapy is an experimental treatment that uses a balloon catheter to deliver internal radiation therapy to the cavity that remains following tumor surgery. A radioactive liquid is injected into the catheter and molds the balloon to the exact edges of the cavity. The liquid stays in the balloon for several days until it and the catheter are removed.
Chemotherapeutic drug research focuses on ways to better deliver drugs across the blood-brain barrier and into the site of the tumor. Since chemotherapeutic drugs work in different ways to stop tumor cells from dividing, several trials are testing whether giving more than one drug, and perhaps giving them in different ways (such as staggered delivery and low-dose, long-term treatment), may kill more tumor cells without causing or lessening damaging side effects than present therapy. Researchers are examining different levels of chemotherapeutic drugs to determine if they are less toxic to normal tissue when combined with other cancer treatments. Other studies are investigating gene therapy as a way to make cancer cells more sensitive to chemotherapy. Research areas include differentiating drugs, osmotic blood-brain barrier disruption, and convection enhanced delivery.
Differentiating drugs change dividing cells into non-dividing cells and can halt tumor growth. An early study using retinoids (made from vitamin A) as an independent treatment for certain tumors showed no significant effect. Scientists are trying retinoids in combination with other chemotherapeutic drugs or treatments to slow the growth of malignant glioma.
Researchers are testing different drugs and molecules to see if they can modulate the normal activity of the blood-brain barrier and better target tumor cells and associated blood vessels.
Osmotic blood-brain barrier disruption uses certain drugs to open blood vessels throughout the brain. Scientists are currently studying whether certain chemotherapeutic drugs, when given with osmotic blood-brain barrier disruption, might be an effective way to kill cancer cells without harmful side effects.
Convection enhanced delivery sends a continuous, uniform stream of toxic drugs into the tumor via catheters that are inserted during surgery. This drug delivery system, which bypasses the blood-brain barrier, is being evaluated in children with recurring brain cancer and in patients whose tumor location prevents its total surgical removal.
Repeat surgical resection has been shown to be beneficial to selected patients with recurrent malignant gliomas. Further studies are ongoing to better define the potential benefits of surgery, including better response to biologic therapy and chemotherapy, improved quality of life, and prolonged survival.
Also under investigation are other ways to help the body respond to improved drug delivery or other cancer treatments. Bone marrow and stem cell transplants may replace blood-forming cells that are killed by chemotherapy, radiation treatment, or a combination of therapies. These transplants, which are given after radiation or chemotherapy, help the patient’s bone marrow recover and produce healthy blood cells. Researchers are studying the effectiveness of these transplants in protecting blood cells in children with certain types of CNS tumors and in other patients with recurrent or hard to treat CNS cancer, who receive higher than normal doses of chemotherapy.
Although many new approaches to treatment appear promising, it is important to remember that all potential therapies must stand the tests of well-designed, carefully controlled clinical trials and long-term follow-up of treated patients before any conclusions can be drawn about their safety or effectiveness. New trial designs are also being developed to more quickly evaluate novel agents and may involve pre-selection of patients based on the molecular abnormality in their tumor.
Past research has led to improved tumor treatments and techniques for many individuals with CNS tumors. Current research promises to generate further improvements. In the years ahead, physicians and individuals who have a CNS tumor can look forward to new, more effective, less toxic forms of therapy developed through a better molecular understanding of the unique traits of CNS tumors.
 Carcinogenicity of radiofrequency electromagnetic fields. World Health Organization/International Agency for Research on Cancer, The Lancet Oncology, Vol. 12, Issue 7, July 2011, pp. 624-626.
Cellular Phone Use and Cancer Risk: Update of a Danish Nationwide Cohort. Schüz et. al., Journal of the National Cancer Institute, Vol. 98, No. 23, December 6, 2006, pp. 1703-1713.
 Central Brain Tumor Registry of the United States, 2011 Statistical Report
 American Brain Tumor Foundation, 2008
 Central Brain Tumor Registry of the United States, 2011 Statistical Report