A brain tumor is a growth of abnormal cells in your brain. A malignant brain tumor grows quickly and can be life-threatening. Brain tumors can be primary (the tumor starts in the brain) and some can be metastatic (the tumor starts elsewhere in your body and spreads to the brain).
Brain tumors can cause many symptoms. Some of the most common symptoms include:
- Morning headaches
- Nausea and vomiting
- Speech problems (e.g., difficulty speaking)
- Vision problems
- Hearing loss
- Difficulty walking or balancing
- Memory or thinking problems
- Feeling tired or sleepy
- Changes in behavior (mood swings)
The doctor may diagnose brain tumors by performing neurological tests and other tests including MRI, CT scan, and biopsy. Treatment options include watchful waiting approach, surgery, radiation therapy, chemotherapy, and targeted therapy. Targeted therapy uses substances that attack cancer cells without damaging normal cells. Many patients receive a combination of medications.
Grades and Types of Brain Tumors
Most normal cells that become old or damaged will die and be replaced with new cells. However, it may not happen in some cases. New cells form when the body does not need them, and old, damaged cells do not die as they should. The buildup of extra cells usually forms a mass of tissue, growth, or lump called a tumor.
Primary brain tumors can be benign (non-cancer) or malignant (cancer):
- Benign brain tumors do not contain cancer cells:
- When removed, benign tumors usually do not grow back.
- Benign brain tumors usually have clear borders or margins. Cells from benign tumors usually invade the surrounding tissue – they do not spread to other parts of the body. However, benign tumors can press on sensitive areas of the brain and cause serious health problems.
- Unlike benign tumors in most other parts of the body, benign brain tumors are generally more serious and life threatening.
- Benign brain tumors can become malignant.
- Malignant brain tumors (also called brain cancer) contain cancer cells:
- Malignant brain tumors are generally more serious and often a threat to life
- Malignant brain tumors tend to grow fast and crowd or invade the nearby healthy brain tissue.
Grades of Tumor
Doctors gradeify brain tumors by grades. Tumor grade refers to how the cells look like under a microscope:
- Grade I: The tissue is benign. The cells look almost like normal brain cells, and grow slowly.
- Grade II: The tissue is malignant. The cells look less like normal cells compared to grade I tumors.
- Grade III: Malignant tissue has cells that look very different from normal cells. Abnormal cells are actively growing (anaplastic).
- Grade IV: Malignant tissue has the most abnormal looking cells and tends to grow rapidly.
Cells in low-grade tumors (Grade I and II) appear more normal and generally grow more slowly compared to cells in high-grade tumors (Grade III and IV).
Over time, a low grade tumor may become a high-grade tumor. However, the transition to high grade tumors is more common to occur in adults than children.
Types of Primary Brain Tumors
There are many types of primary brain tumors. Primary brain tumors are named according to the type of cell or part of the brain where the tumor begins. For example, most primary brain tumors start in the glial cells. This type of tumor is called a glioma.
Among adults, the most common types of brain tumors include:
- Astrocytoma: These tumors arise from star-shaped glial cells called astrocytes. The grade may vary from I to IV. In adults, astrocytoma most often appears in the cerebrum.
- Grade I or II astrocytoma: This can be referred to as a low grade glioma.
- Grade III astrocytoma: This can be called high grade or anaplastic astrocytoma.
- Grade IV astrocytoma: This can be called a glioblastoma or malignant astrocytoma glioma.
- Meningioma: This tumor appears in the meninges and it can be grade I, II, or III. Usually benign (grade I) and growing slowly.
- Oligodendroglioma: These tumors arise from the cells that make the fatty substances covering and protecting the nerves. It usually occurs in the cerebrum and affects middle aged adults. The severity can be grade II or III.
Among children, the most common types of brain tumors are:
- Medulloblastoma: This tumor usually appears in the cerebellum. Sometimes, this is called a primitive neuroectodermal tumor. Classified as Grade IV.
- Grade I or II astrocytoma: In children, this low grade tumor occurs anywhere in the brain. The most common astrocytoma among children is juvenile pilocytic astrocytoma. Classified as Grade IV.
- Ependymoma: These tumors arise from the cells lining the ventricles or central canal of the spinal cord. It is most commonly found in children and young adults. It can be classified as grade I, II, or III.
- Stem glioma: This tumor occurs at the very bottom of the brain. This can be a low grade or high grade tumor. The most common type is diffuse intrinsic pontine glioma.
Risk Factors of Brain Tumors
The first thing that comes to mind when you are diagnosed with a brain tumor may be “Why?”. However, no one knows the exact cause of a brain tumor. Doctors are rarely able to identify why one person develops a brain tumor, and the other does not.
Researchers are studying people with certain risk factors that are more likely to develop brain tumors. A risk factor is something that can increase your chances of getting a disease.
Research has found the following risk factors for brain tumors:
- Ionizing radiation: Ionizing radiation from high doses of X-rays (such as radiation therapy from large machines aimed at the head) and other sources can cause cell damage that leads to tumors. People who are exposed to ionizing radiation may have an increased risk of a brain tumor, such as a meningioma or glioma.
- Family history: Brain tumors rarely run in families. Few families have multiple members with brain tumors.
Researchers are studying whether using cell phones, experiencing head injuries, or being exposed to certain chemicals at work or magnetic fields are important risk factors. Studies have not shown a consistent association between these risk factors and brain tumors, but additional research is needed.
Symptoms of Brain Tumors
Symptoms of a brain tumor depend on the size, type, and location. Symptoms may occur when a tumor presses on a nerve or damages a part of the brain. Also, it may arise when the tumor blocks fluid flowing through and around the brain, or when the brain swells due to fluid buildup.
These are the most common symptoms of a brain tumor:
- Headaches that tend to worsen in the morning
- Nausea and vomiting
- Speech problems (e.g., difficulty speaking)
- Vision problems
- Hearing loss
- Difficulty walking or balancing
- Memory or thinking problems
- Feeling tired or sleepy
- Changes in behavior (mood swings, concentration ability)
- Single or multiple muscle twitches, jerks, spasms (motor seizure or convulsions)
- Numbness or tingling in the arms or legs
Usually, these symptoms are not due to a brain tumor. Other health problems can cause these symptoms. If you experience any of these symptoms you should tell your doctor so that the problem can be diagnosed and treated.
Diagnosis of Brain Tumors
If you have symptoms that suggest a brain tumor, your doctor will conduct a physical exam and ask about your personal and family health history. You may undergo one or more of the following tests:
- Neurological examination: The doctor assesses your vision, hearing, level of alertness, muscle strength, coordination, and reflexes. The doctor also examines your eye for swelling caused by the tumor pressing on the nerves that connect the eye and brain.
- MRI: A large machine with strong magnets connected to a computer used to create detailed images of the area inside your head. Sometimes, a special dye (contrast material) is injected into a vein in your arm or hand to show differences in brain tissue. These images can show abnormal parts, such as a tumor.
- CT scan: An x-ray machine connected to a computer that takes a series of detailed pictures of your head. You may receive a contrast material by injection into a vein in your arm or hand. Contrast material will make abnormal parts easier to see.
The doctor may order other tests:
- Angiogram: A dye injected into the bloodstream that makes blood vessels in the brain visible on an x-ray. If a tumor is present, x-rays can show the tumor or blood vessels (feeding the cancer) in the area
- Spinal tap: The doctor may take a sample of cerebrospinal fluid (fluid that fills the spaces around the brain and spinal cord). This procedure is performed under local anesthesia. The doctor uses a long, thin needle to remove fluid from the bottom of the spine. The spinal tap test takes about 30 minutes. You need to lie flat for a few hours afterward to prevent you from having a headache. The lab checks the fluid for cancer cells or other signs of problems.
- Biopsy: The removal of tissue to look for tumor cells is called a biopsy. The pathologist looks at the cells under a microscope to check for abnormal cells. A biopsy can show cancer, tissue changes that may cause cancer, and other conditions. A biopsy is the only certain way to diagnose a brain tumor, identify its grade, and suggest the right treatment.
Surgeons may obtain tissue to look for tumor cells in two ways:
- Biopsy at the same time as treatment: The surgeon takes a tissue sample when you have surgery to remove part or all of the tumor.
- Stereotactic biopsy: You may get local or general anesthesia and wear a rigid head frame for this procedure. The surgeon makes a small incision in the scalp and drills a small hole (a burr hole) into the skull. CT or MRI is used to guide a needle through the burr hole to the tumor site. The surgeon takes a tissue sample with a needle. A needle biopsy may be used when the tumor is deep inside the brain or in a part of the brain that cannot be operated on.
However, if the tumor is in the brain stem or certain other areas, the surgeon may not be able to remove the tissue from the tumor without damaging normal brain tissue. In this case, the doctor uses MRI, CT, or other imaging tests to learn as much as possible about the brain tumor.
Treatment for Brain Tumors
In patients with brain tumors, several treatment options are available. The options include surgery, radiation therapy, and chemotherapy. Many patients often get a combination of treatments.
Treatment options depend on the following:
- Types and grades of brain tumors
- The tumor’s location
- The tumor’s size
- The patient’s age and general health
For some types of brain cancer, the doctor also needs to know if cancer cells are found in the cerebrospinal fluid.
Your doctor can explain your treatment options, expected results, and possible side effects. It is common for patients to have side effects as a result from cancer therapy that may damage healthy cells and tissues. Before starting treatment, ask your healthcare provider about possible side effects and how medication may affect your normal activities. You can work together with your health care team to develop a treatment plan that meets your medical and personal needs.
You may want to talk to your doctor about taking part in a clinical trial – a research study on a new treatment method. Your doctor may refer you to a specialist, or you may ask for a referral. Specialist doctors treating brain tumors include neurologists, neurosurgeons, oncologists, and radiation oncologists.
Brain tumor surgery
In general, surgery is the first recommended treatment option for most brain tumors. Before the surgery begins, you may be given general anesthesia, and have your scalp shaved. It may not be necessary to shave the whole head. The surgical procedure to open the skull is called a craniotomy. The surgeon makes an incision in the scalp and uses a special type of saw to remove a piece of bone from the skull.
You may be awake when the surgeon removes part or all of the brain tumor. The surgeon removes as much of the tumor as possible. You may be asked to move your feet, count numbers, say the alphabet, or tell a story. Your ability to follow these commands helps the surgeon protect important parts of the brain.
After the tumor is removed, the surgeon closes the hole in the skull with a piece of bone or with a piece of metal or cloth. The surgeon then closes the incisions in the scalp.
In some cases, surgery may not be an option. If the tumor is in the brain stem or certain other areas, the surgeon may not be able to remove the tumor without damaging normal brain tissue. People who cannot undergo surgery may be recommended radiation therapy or other treatments instead
You may experience headaches or discomfort in the first few days after surgery. However, medications may help control pain. Before surgery, you should ask your healthcare provider about how to relieve pain. This is done so that your team can adjust post-treatment plans after the surgery. You may also feel tired or weak. Recovery period after surgery varies from patient to patient. You may have to spend several days in the hospital.
Other common problems might occur after surgery for brain tumors. The brain may swell or fluid may accumulate in the skull. Your healthcare team will monitor you for signs of swelling or fluid buildup. You may receive steroids to help relieve swelling. A second surgery may be required to drain the liquid. The surgeon may place a long, thin tube (shunt) in the ventricles of the brain (in some patients, a shunt is placed before surgery on a brain tumor.) This tube is pushed under the skin to another part of the body, usually the stomach. Excess fluid is carried from the brain and drained into the stomach. Sometimes, the fluid is rushed to the heart instead.
Infection is another complication that you may develop after surgery. If this happens, your healthcare team will give you antibiotics.
Brain surgery may harm normal tissue. Brain damage may turn into a serious problem. This can lead to thinking, seeing, or speaking problems. It can also cause personality changes or seizures. Most of these problems may resolve or go away over time. However, brain damage can be permanent. You may require physical therapy, talk therapy, or occupational therapy.
Radiation therapy kills brain tumor cells with high-energy X-rays, gamma rays, or protons. Radiation therapy is usually done after surgery. The radiation kills any tumor cells that may remain in the area. Sometimes, people who are unable to undergo surgery will go through radiation therapy instead.
The doctor performs external and internal radiation therapy to treat brain tumors:
- External radiation therapy: You may go to a hospital or clinic for treatment. A large machine outside the body directs radiation beams to the head. Since cancer cells may invade the normal tissue around the tumor, the radiation may be aimed at the tumor and nearby brain tissue, or throughout the brain. Some people may require the radiation that aims at the spinal cord as well. The treatment schedule depends on your age, the type, and size of the tumor. Fractionated external beam therapy is the most commonly used method of radiation therapy for people with brain tumors. Giving a total dose of radiation over several weeks helps protect the healthy tissue in the tumor area. Treatment is usually done 5 days a week for several weeks. The visit usually lasts less than an hour, and each treatment only takes a few minutes. Several treatment centers are studying other ways to provide external beam radiation therapy:
- Intensity-modulated radiation therapy or 3-dimensional Conformal radiation therapy: This treatment uses a computer to target brain tumors more closely to reduce damage to healthy tissue.
- Proton beam radiation therapy: The source of radiation is from protons rather than X-rays. The doctor directs a proton beam at the tumor. The radiation dose to normal tissue from a proton beam is smaller than the dose from an x-ray.
- Stereotactic radiation therapy: A narrow beam of X-rays or gamma rays is directed at the tumor from different angles. For this procedure, you use stereotactic frames. This treatment may be given in a single visit (stereotactic radiosurgery) or several visits.
- Internal radiation therapy (implanted radiation therapy or brachytherapy): Internal radiation is not commonly used to treat brain tumors and is still being studied. The radiation comes from radioactive material that is usually contained in tiny implants called granules. The granules are placed in the brain and emit radiation for months. The granules do not need to be removed once the radiation disappears.
Some patients may experience no or few side effects after treatment. Rarely, people may experience nausea for several hours after external radiation therapy. Your healthcare team may suggest ways to help you deal with this problem. Radiation therapy can also cause you to become very tired with each radiation treatment. Getting rest is important, but the doctor usually advises patients to try to stay as active as possible.
External radiation therapy usually causes hair loss in the head area being treated. Your hair may grow back within a few months. Radiation therapy may also make your scalp and ears red, dry, and tender. You will be suggested ways by your healthcare team to resolve this problem.
In some cases, radiation therapy causes brain tissue to swell. You may experience headaches or feel pressure. The healthcare team will be watching for signs of this problem. Also, they may provide medication to reduce discomfort.
Radiation may also kill healthy brain tissue. Although rare, these side effects may cause headaches, seizures, or even death. Radiation may harm the pituitary gland and other areas of the brain. For children, this damage may cause learning problems or slow growth and development. In addition, radiation increases the risk of secondary tumors later in life.
Chemotherapy, the use of drugs to kill cancer cells, is sometimes used to treat brain tumors. Medicines can be given in the following ways:
- Oral or intravenous: Chemotherapy may be given during and after radiation therapy. The drugs enter the bloodstream and travel throughout the body. Medicines may be given in an outpatient hospital setting, at the doctor’s office, or at home. Usually, you do not have to stay in the hospital.
The side effects of chemotherapy depend on the type and the dose of drugs given. Common side effects include nausea and vomiting, loss of appetite, headache, fever and chills, and fatigue. If the medicine lowers the level of healthy blood cells, you are more likely to get infections, easy bruising or bleeding, and feel very weak or tired. Your healthcare team will check your low blood cell levels. Some of the side effects may be reduced with medication.
- Wafer insertion into the brain: In some adult patients with high-grade glioma, the surgeon implants multiple wafers into the brain. Each wafer is about the size of a coin. Over several weeks, the wafers dissolve – releasing drugs to the brain. The drug kills cancer cells. This may help prevent tumors from recurring in the brain after surgery to remove the tumor.
People who receive implants (wafers) containing the drug are monitored by the healthcare team for signs of infection after surgery. Infections may be treated with antibiotics.
Brain Tumor Rehabilitation
Rehabilitation can be a vital part of a treatment plan. The goals of rehabilitation depend on your needs and how the tumor has affected your ability to carry out daily activities. Some people may not regain all the abilities they had before the brain tumor and its treatment. However, your healthcare team is doing their best to help you return to normal activities as soon as possible.
Several types of professional therapists may help:
- Physical therapist: Brain tumors and its treatment may cause paralysis. It may also cause weakness and balancing problems. Physical therapists help people regain strength and balance.
- Speech therapist: A speech therapist helps people who have difficulty speaking, expressing thoughts, or swallowing.
- Occupational therapist: Occupational therapists help people learn to manage activities of daily life, such as eating, using the toilet, showering, and dressing.
- Physical medicine specialist: This specialist doctor helps people with brain tumors stay as active as possible as well as help people recover lost abilities and return to daily activities.
Children with brain tumors may require special needs. Paediatric patients may be provided with tutors at the hospital or at home. Children who have problems learning or remembering what may require special tutors to assist them when they return to school.
Brain and Spinal Tumors – A Brief Summary
What Are Brain and Spinal Tumors?
Tumors of the brain and spinal cord are abnormal growths of tissue found inside the skull or the bony spinal column. The brain and spinal cord are the primary components of the central nervous system (CNS). Benign tumors are non-cancerous, and malignant tumors are cancerous. The CNS is housed in a rigid and bony site (the skull and spinal column), so any abnormal growth, whether benign or malignant, can put pressure on sensitive tissues and impair function. Tumors that originate in the brain or spinal cord are called primary tumors.
Most primary tumors are caused by out-of-control growth between the cells that surround and support neurons, certain genetic diseases (such as neurofibromatosis type 1 and tuberous sclerosis), or from exposure to radiation or cancer-causing chemicals. Metastases, or secondary tumors in the CNS are caused by cancer cells that break away from a primary tumor located in other areas of the body. Tumors can place pressure on sensitive tissues and impair function. Symptoms of a brain tumor include headaches, seizures, nausea and vomiting, poor vision or hearing, changes in behavior, unclear thinking, and unsteadiness. Symptoms of a spinal cord tumor include pain, numbness, and paralysis. Diagnosis is usually made after neurological examination, special imaging techniques (computed tomography, and magnetic resonance imaging, positron emission tomography), laboratory tests, and biopsy (in which a sample of tissue is taken from the suspected tumor and examined).
Is there a cure?
The three most commonly used treatments are surgery, radiation, and chemotherapy. The doctor may also prescribe steroids to reduce tumor-related swelling within the CNS.
What is the prognosis?
Symptoms of brain and spinal cord tumors generally develop slowly and get worse over time if left untreated. Tumors may be benign or malignant and determined by grades that reflect the degree of malignancy. This grade can help doctors determine how to treat a tumor and predict the possible outcome, or prognosis, for the patient.
Overview of Brain and Spinal Cord Tumors
Diagnosis of a brain or spinal cord tumor may bring uncertainty and anxiety not only to the patient, but also those who are close (friends and family). It can be easily understandable if you are worried about things that you may know little o nothing about (advanced technology in medical science, new medical testing, or medications)
This guide will provide you with a better understanding of brain and spinal cord tumors — its treatment options and the latest research to find safer and more effective ways to diagnose and treat them. You can take care of yourself by studying your diagnosis and discussing it with your doctor.
What are brain tumors and spinal cord tumors?
Tumors of the brain and spinal cord are found in the tissues inside the skull or spine, which make up the central nervous system (CNS). Tumors are masses of cells that form new growths or are present at birth (congenital). Tumors occur when genes regulating cell growth become damaged or mutated, allowing cells to grow and divide out of control. Tumors may form anywhere in the body.
Depending on its type, the growing tumor may kill healthy cells or interfere with their function. Tumors may move or compress sensitive tissue and block the blood flow and other fluids — causing pain and inflammation. Tumors can also block the normal flow of electricity in the brain or nerves that signal to and from the brain. Some tumors cause no trouble at all.
There are more than 120 types of brain tumors and spinal tumors. Some are named according to the most similar type of normal cell (such as a glioma) or location (such as a meningioma, which forms in the lining of the brain and spinal cord).
The following overview describes 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:
- Brainstem – This is the lowest part of the brain (above the neck) that connects to the spinal cord and relays information between the brain and body using long nerve bundles. The brain stem controls basic life-sustaining functions, including blood pressure, heart rate, 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. The cerebrum controls functions including movement, touch, judgement, learning, speech, emotions, and thinking.
- Cerebellum – Located in the lower rear of the brain, above the brainstem, the cerebellum controls balance, helps maintain equilibrium, and coordinates complex muscle movements such as walking and speaking.
The two parts of the brain, or hemispheres, use nerve cells (neurons) to speak with each other. Each side of the brain controls movement and function on the other side of the body. In addition, each hemisphere has four sections, called lobes, that handle different neurological functions.
The frontal lobes manage voluntary movement, such as writing, and allows us to set and prioritize goals. A frontal lobe tumor can cause changes in personality, intelligence, reasoning, and behavior; affect coordination and walking, and cause speech problems. The temporal lobe is associated with perception, memory, and understanding of sounds and words. A tumor in the temporal lobe may cause speech and hearing problems, fainting, seizures, or a sensation such as a feeling of fear. A parietal lobe allows us to simultaneously receive and understand sensations such as pressure and pain. Parietal lobe tumors may cause difficulty understanding or saying words, problems with coordination, seizures, and numbness or weakness on one side of the body. The occipital lobe receives and processes light and visual images, and detects motion. Occipital lobe tumors can affect the field of vision, usually on one side of the view, and how we understand the written word.
Three layers of protective tissue (called the meninges) cover the brain – the thick dura mater (outer layer), arachnoid (middle), and pia mater (innermost to the brain).
Brain tumors in infants and adults tend to affect the cerebrum. Brain tumors in children ages 1-12 years are more often found in the cerebellum.
The spinal cord — an extension of the brain — lies protected inside the spine. 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 the arm or information from the skin that signals pain.
Tumors that form on or near the spinal cord can disrupt communication between the brain and nerves or limit the bone marrow’s blood supply. Due to the narrow spine, a tumor located here–unlike brain tumors–can cause symptoms on both sides of the body at the same time.
Tumors growing in the cervical spine can cause pain that appears to originate from the neck or arms, and tumors that grow in the lower lumbar spine can trigger back or leg pain.
The three main groups of spinal cord tumors describe where they are found. An extradural tumor grows between the inner surface of the spinal canal and the hard 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 within the spinal cord; and extrinsic, where the tumor forms on the outside and presses on the cord as it grows.
Frequently Asked Questions about CNS Tumors
What are benign tumors and malignant tumors?
Wherever they are located in the body, tumors are classified as benign or malignant.
Benign tumors are slow-growing, non-cancerous cell masses that have defined edges and do not spread to other parts of the body. The 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 rapidly invade surrounding tissue and often have margins that are difficult to define, making it difficult to remove the entire tumor surgically.
What are primary and metastatic tumors?
Primary CNS tumors are growths that start in the brain or spinal cord. Primary tumors may be malignant or benign and are identified according to 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 breaking away from primary tumors that develop in non-CNS parts of the body. These tumors are named after the type of cancer that caused them. Metastatic (also called metastases) tumors to the brain occur in about a quarter of all cancers that develop in other parts of the body, such as lung, breast, or kidney cancer; or melanoma, a form of skin cancer. Metastatic tumors are more common than primary tumors and occur more often in adults than in children.
Metastatic spinal tumors usually form within the bony covers of the spine but may also invade the spinal canal from the chest or abdomen.
Cancer elsewhere in the body can easily cause tumors within the brain and spinal cord, but CNS tumors rarely spread outside the nervous system.
What causes CNS tumors?
Researchers really do not know why primary brain tumors and spinal cord tumors develop. Possible causes under investigation include viruses, defective genes, exposure to certain chemicals and other harmful substances, and immune system disorders. Although it has been linked to several types of cancer, smoking, alcohol consumption, and certain dietary habits have not been linked to primary CNS tumors.
In a small number of individuals, CNS tumors may arise from certain genetic diseases, such as neurofibromatosis and tuberous sclerosis, or exposure to radiation. It is currently unclear whether non-ionizing radiation (radio waves) from cell phone use increases the risk of developing a brain tumor.
Brain and spinal cord tumors are not contagious or, at this point, 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 a person will develop a tumor. Brain tumors are more common in men than in women and occur most common in middle-aged to older people. These tumors 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 primary CNS tumors include race (Caucasians are more likely to develop CNS tumors 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 brain tumors.
How are tumors graded?
The generally accepted scale for the grading of CNS tumors was approved by the World Health Organization in 1993. Grading is based on the arrangement and location of tumor cells. Tumors may also be classified as low-grade (slow 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 after a biopsy or during surgery.
Grade I tumors grow slowly and generally do not spread to other parts of the brain. Often, it is 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 the surrounding tissue, and can become higher grade tumors. Treatment varies according to the location of the tumor and may require chemotherapy, radiation, or surgery followed by close observation.
Grade III tumors are malignant and can spread rapidly to other CNS tissues. Tumor cells will look different from the surrounding tissue cells. Aggressive treatment, often using a combination of chemotherapy, radiation, and / or surgery, is needed.
Grade IV tumors invade nearby tissue very quickly and are difficult to treat. Cancer tissue will look very different from the surrounding tissue. Aggressive treatment is required.
What are the possible symptoms?
Brain and spinal cord tumors cause a wide variety of symptoms, which can make detection complicated. Symptoms depend on the type of tumor, location, size, and growth rate. Certain symptoms are quite specific because they are caused by damage to specific areas of the brain. Symptoms generally develop slowly and get worse 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 brain tumors in adults include headaches, seizures, balance or coordination problems, loss of muscle control, hydrocephalus, and changes in personality or behavior.
Headaches are the most common symptom of a brain tumor. Headaches may get worse, become more frequent or constant, and recur, often at irregular intervals. Headaches can get worse when coughing, changing posture, or straining and may be severe when you wake up.
Seizures can also occur, with symptoms that may include convulsions, loss of consciousness, or loss of bladder control. Seizures that first begin in adulthood (in someone who has never had an accident or who has a disease that caused the seizure) are the main warning signs of a brain tumor.
Nausea and vomiting may worsen 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, behavioral, and cognitive changes can include psychotic episodes and problems with speech, language, thinking, and memory.
Motor problems may include weakness or paralysis, lack of coordination, or a gradual loss of sensation or movement in an arm or leg. Sudden, marked changes in handwriting may be a sign of a tumor.
Balance problems can include dizziness, difficulty walking, clumsiness, or loss of normal balance control.
Hydrocephalus and increased intracranial pressure occur when a tumor blocks the flow of cerebrospinal fluid (CSF) that surrounds the brain and spinal cord. Symptoms may include headache, nausea, and vomiting.
Other symptoms may include abnormal endocrine or abnormal hormone regulation, difficulty swallowing, facial paralysis and sagging eyelids, fatigue, weakened sense of smell, or disturbed sleep and sleep pattern changes.
Common symptoms of spinal cord tumors 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. The pain is often progressive and can be a burning or aching sensation.
Numbness or sensory changes can include decreased sensitivity of the skin to temperature and progressive numbness or loss of sensation, especially in the legs.
Motor problems and loss of muscle control can include muscle weakness, spasticity (in which the muscles remain stiff contracted), and impaired bladder and / or bowel control. When left untreated, symptoms may worsen including muscle atrophy, decreased muscle strength, an abnormal walking rhythm known as ataxia, and paralysis.
Symptoms may spread to different parts of the body when one or more tumors extend to several parts 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 the patient’s symptoms, personal and family medical history, and the results of a physical examination and special tests and techniques.
Neurological examination – 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 specialists to run them and analyze the results.
The doctor will order one or more imaging techniques that provide a very detailed view of the body’s structure, including tissues, organs, bones, and nerves. If a tumor is present, diagnostic imaging will confirm the diagnosis and help the doctor determine the type of tumor, detect swelling and other related conditions, and, over time, check the results of treatment.
Computed Tomography (CT) uses X-rays and a computer to produce fast, detailed cross-sectional images or “slices” of organs, bone, and tissue, including tumors. It can also be helpful for detecting calcium buildup, 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 a two-dimensional slice or a detailed three-dimensional model of the tissue that is being scanned. MRI takes longer than CT but is more sensitive and provides a better view of tumors that are located near the bone.
CT or MRI scans for tumors are usually done before and after administering a “contrast” agent (such as a dye) that is inserted into a vein. Many tumors appear brighter on the scans 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 strokes, and show the distance between specific brain function and tumors in specific areas of the brain.
Magnetic Resonance Spectroscopy (MRS) provides doctors with a chemical picture of the tissues being studied. MRS uses a magnetic field and radio waves MRI scanner to measure and analyze the chemical makeup of tissue samples.
Positron Emission Tomography (PET) provides computer-generated two- and three-dimensional scans of the brain’s chemical activity and cellular function. PET tracks and measures the brain’s use of glucose (sugar, used by the brain for energy) that is attached to small amounts of radioactivity and is injected into the bloodstream. Since malignant tissue uses more glucose than normal tissue, it usually appears brighter on scans than surrounding tissue.
Single Photon Emission Computed Tomography (SPECT) studies blood flow to tissues. Certain tumors grow new blood vessels to increase blood supply and nutrients. Radioactive isotopes are injected intravenously and traced as they travel into the skull. A sophisticated computer processes and accumulates the data into detailed three-dimensional images of activity within the brain.
An angiography (or arteriogram) can distinguish certain types of tumors that have distinctive patterns 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 are taken as the dye travels to the brain. In many situations angiography has been replaced by noninvasive tests such as CT and MRI.
Testing blood, urine, and other substances can provide clues about tumors and monitor levels of therapeutic drugs.
Additional tests may include an electroencephalogram, or EEG, which monitors brain activity through the skull (a tumor can disrupt the normal flow of brain wave activity and cause seizures); Cerebrospinal fluid analysis (CSF), in which a small amount of cerebrospinal fluid is removed by a special needle and examined for abnormal cells or unusual levels of various compounds that indicate brain or spinal cord tumors; 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 in individuals with very large brain tumors.
Diagnosing the different types of brain tumors is often difficult. Individuals should consider asking a primary care doctor or oncologist for a second opinion, especially from a neurologist or neurosurgeon, as there may be new information available and some tumors may change grade or recur. Even a second opinion confirming the original diagnosis can help people better prepare for their care and treatment.
How are brain and spinal cord tumors treated?
A team of specialist doctors advise and assist individuals throughout treatment and rehabilitation. These doctors may include:
- Neurologists are specialists in nervous system disorders.
- Oncologists are specialists in cancer
- Neurological oncologists are neurologists or oncologists who specialize in nervous system tumors.
- Neuroradiologists are doctors trained in reading diagnostic imaging results who specialize in the CNS.
- Pathologists are clinical physicians who diagnose tissue or cells diseases using a variety of laboratory tests.
- Neurosurgeons are brain or spinal cord surgeons.
- Radiation oncologists are doctors who specialize in using radiation to treat individuals with cancer.
The team will recommend a treatment plan based on the tumor’s location, type, size and aggressiveness, as well as on the individual medical history, age, and general health.
Initial treatment for CNS tumors may involve a variety of medications, 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 may occur after a tumor diagnosis, and medications to fight nausea caused by various treatments
Malignant tumors require some form of treatment, while some small benign tumors may only require 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 accessible tumors – tumors that can be removed without unacceptable risk of neurological damage. Surgery is aimed at removing all or as much of the tumor as possible (called resection or excision) and often slows worsening of neurological function.
Inaccessible or inoperable tumors are tumors that cannot be removed surgically because of the risk of severe nervous system damage during the surgery. These tumors are often located deep in 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 surgery to remove a small part of the skull to take a sample of tumor tissue. A biopsy can sometimes be performed with a needle inserted through a small hole. A small piece of tissue stays in the hollow needle when it is removed from the body. The pathologist will stain and examine the tissue for certain changes that indicate cancer and grade them to reflect the degree of malignancy.
If the sample is cancerous, the surgeon will remove as much of the tumor as possible. For some primary brain tumors, surgery is not possible to remove all malignant cells. Malignant brain tumors generally recur from cells that have spread from the original tumor mass to the surrounding brain tissue. In contrast, many benign tumors and secondary metastatic tumors can be completely removed surgically.
In some cases, the 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 used to divert the flow of CSF from the central nervous system to other parts of the body, where it can be absorbed as part of the normal circulatory process.
Fortunately, research has led to advances in neurosurgery that have made it possible for doctors to completely remove many tumors previously deemed inoperable. These new techniques and tools allow neurosurgeons to operate within the tight and vulnerable limits of the CNS. Some of the tools used in the operating room include a surgical microscope, an endoscope (a small tube attached to a video camera), and miniature precision instruments that allow surgery to be performed through tiny incisions in the brain or spine.
Intraoperative MRI uses a special type of MRI to provide real-time evaluation of the surgery. Constantly updated images provided during surgery allow doctors to see how much tumor material has been removed. Intraoperative MRI can also help doctors choose the best surgical approach and monitor any complications during surgery.
Navigational equipment used in computer-guided, or stereotactic neurosurgery, provides doctors with a precise, three-dimensional map of a person’s spine or brain as the operation progresses. The computer uses preoperative diagnostic images of the individual to reduce the risk of damage to surrounding tissue.
Intraoperative nerve monitoring test such as evoked potential use real-time recording of nerve cell activity to determine the role of specific nerves and monitor brain activity during surgery. Small electrodes are used to stimulate nerves and measure their electrical response (or evoked potential). Some surgeries may be performed while the individual is awake under monitored anesthesia care, rather than under general anesthesia. This allows doctors to monitor a person’s speech and motor functions while the tumor is being removed.
A possible side effect of surgery is swelling around the site of the tumor – which can be treated with steroids. Bleeding into the tumor site or infection are other serious risks of brain surgery.
In the case of metastatic tumors, doctors usually treat the original cancer. However, if there are only one or two metastases to the brain or if the metastatic tumor is causing serious disability or pain, the doctor may recommend surgery — even if the original cancer has not been controlled.
Surgery may be the start 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 prevent them from multiplying. When successful, this therapy shrinks the tumor mass but does not actually remove it. Radiation therapy can be used to treat tumors that are inaccessible to surgery or tumor cells that may remain after surgery.
Depending on the type and stage of the tumor, radiation treatment may be given externally, using a focused beam of energy or charged particles 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 damaged tumor cells cannot.
A radiation oncologist will explain the therapy and how much radiation is required. Treatment often starts a week after surgery and may continue for several weeks. Depending on the type and location of the tumor, patients may be able to receive a modified form of therapy to reduce damage to healthy cells and improve overall treatment.
Externally-administered radiation therapy does not pose a risk of radioactivity to the patient or to family and friends. Types of external radiation therapy include:
Whole brain radiation is generally used to shrink some cancer tumors, rather than targeting individual tumors. It can be given as the only form of treatment or before 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 tissues from outside the body. It is used to treat large tumors or those that may have spread to surrounding tissue.
Three-dimensional conformal radiotherapy (3D-CRT) uses diagnostic imaging to prepare computer-generated, accurate three-dimensional images of the tumor and surrounding tissue. The computer then coordinates and sends multiple beams of radiation to the exact shape of the tumor, leaving nearby organs and surrounding tissue.
Intensity modulated radiation therapy (IMRT) is similar to 3D-CRT but varies the intensity of hundreds of individual radiation beams to deliver a more precise dose to the tumor or to specific areas within it. IRMT can deliver a highly effective radiation dose to the tumor, with little exposure to the surrounding tissue.
Hyperfractionation involves administering two or more smaller amounts of radiation per day than a single, larger dose. This can provide more radiation to certain tumors and reduce damage to normal cells.
Radiosurgery is usually a one-time treatment that involves a large amount of sharply focused radiation aimed at the brain tumor. Stereotactic radiosurgery uses computer imaging to direct focused radiation precisely into the tumor from multiple angles. It does not actually cut into the person, but similar to other forms of radiation therapy, it impairs the ability of tumor cells to grow and divide. Stereotactic radiosurgery is usually used to treat surgically inaccessible tumors. It may also be used at the end of conventional radiation treatments. 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 linear high-energy transfer radiation, LINAC forms the beam to match the shape of the tumor, avoiding surrounding tissue. A special machine that rotates around the head then shoots a uniform dose of radiation into the tumor.
- Gamma knife® radiosurgery focuses more than 200 rays of gamma radiation into one intersecting beam that is fired at the tumor. It also uses computer imaging to prepare a tumor model. This single treatment takes between one to four hours and is often recommended for tumors that are inaccessible or difficult to treat.
Both procedures may be given on an outpatient basis but an overnight hospital stay is often recommended.
Proton beam therapy directs high-energy proton beams directly to the site of the tumor, 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 a 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, radiation is inserted during surgery or using imaging and catheters. Radiation can 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 of time.
Individuals may need to be hospitalized for several days after this procedure as the radiation may extend outside their body and may harm others. The radiation becomes less active each day until it is safe for individuals who have been treated to be around other people.
Side effects of radiation therapy vary from person to person and are usually temporary. Side effects usually start about two weeks after treatment begins and may include fatigue, nausea, vomiting, reddened or sore skin in the area receiving treatment, headache, hearing loss, problems with sleeping, and hair loss (although the hair usually grows back after treatment stops). Radiation therapy in young children, especially those children age 3 younger, can cause problems with learning, processing information, thinking, and growing.
Chemotherapy uses strong drugs to kill cancer cells or stop them from growing or dividing. These medications are usually given by pill or injection and travel through the body to the brain, or they can be given surgically using a dissolved wafer soaked in chemotherapy drugs. These wafers slowly release a high concentration of medicine to kill any remaining malignant cells. Chemotherapy can also be given to kill cancer cells in the spine.
Chemotherapy is given in cycles to be more effective in damaging cancer cells and giving normal cells time to recover from damage. The oncologist will base treatment on the type of cancer, the drugs used, the frequency of administration, and the number of cycles required.
Individuals may receive chemotherapy to shrink the tumor before surgery (called neo-adjuvant therapy), combined with radiation therapy, or after radiation treatment (called adjuvant therapy) to destroy any remaining cancer cells. Metronomic therapy involves the continuous administration of low-dose chemotherapy to block the mechanisms that stimulate the growth of new blood vessels needed to feed the tumor. Chemotherapy is also used to treat CNS lymphoma and tumors that are inaccessible 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 chemotherapy includes temozolomide, carmustine (also called BCNU), lomustine, tamoxifen, carboplatin, methotrexate, procarbazine, and vincristine. Patients should make sure to discuss all options with their medical team.
Chemotherapy side effects may include hair loss, nausea, digestive problems, reduced bone marrow production, and fatigue. Treatment can also harm normal cells that grow or divide at the same time, but these cells usually recover and problems stop after treatment is complete.
Alternative and complementary approaches may help tumor patients better cope with their diagnosis and treatment. Some of these therapies, however, can be dangerous if used during or after cancer treatment and should be discussed with a doctor beforehand. Common approaches include nutritional and herbal supplements, vitamins, special diets, and mental or physical techniques to reduce stress.
What is the prognosis?
Each patient is different. Prognosis depends largely on prompt diagnosis and treatment, the person’s age and general health, whether the tumor is malignant or benign, the size and location of the tumor, the tumor grade, and response to therapy. A person whose entire tumor has been successfully removed may fully recover. Generally, the prognosis is worse 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.
Follow-up and long-term follow-up are recommended because many tumors are resistant to treatment and tend to recur.
Normal tissue and nerves that may have been damaged or traumatized by the tumor or treatment will need time to heal. Some post-treatment symptoms will go away 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 conducted?
Scientists continue to investigate ways to better understand, diagnose, and treat CNS tumors. Some of today’s treatment regimens were experimental therapies only a decade ago. Current clinical research of genetic risk factors, environmental causes, and molecular mechanisms of cancer may translate into treatments of, or perhaps cures for, these tumors in the future.
Much of this work is supported by the National Institutes of Health (NIH), through the collaborative efforts of the National Institute of Neurological Disorders and Stroke (NINDS) and the National Cancer Institute (NCI), as well as non-profit groups, pharmaceutical companies, and private institutions. Some of this research is conducted through the collaborative neuroscience and cancer research community at NIH or through research grants to academic centers across the United States.
The co-sponsored branch of the NCO-NINDS Neuro-Oncology coordinates research to develop and test the effectiveness and safety of new therapies for people with CNS tumors. These experimental treatment options may include new drugs, combination therapy, gene therapy, biological immunological agents, surgery, and radiation.
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 a mouse model that mimics human CNS cancer, which may accelerate the discovery of potential treatments in humans.
Beyond their efforts to develop the necessary resources, scientists at NIH and at universities across the US are exploring different approaches to treating CNS tumors. These experimental approaches include boosting the immune system to better combat tumor cells, developing therapies that target tumor cells while reserving normal cells, making improvements in radiation therapy, disabling tumors using genes attached to viruses, and determining biomarkers that may predict the response of the CNS tumors against certain treatments.
Biological therapy involves increasing the body’s overall immune response to recognize and fight cancer cells. The immune system is designed to attack foreign substances in the body; because cancer cells are not foreign, they usually do not produce much of an immune response. The researchers are using different methods to provoke a strong immune response against tumor cells. Proteins such 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 to proteins on the surface 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 enhance the immune response and target tumor cells. Scientists are also experimenting with genetically altered T-cells from patients’ own bodies, which are cultured with antigens and injected directly into the brain after 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 fight off bacteria and viruses. Monoclonal antibodies are multiple copies of a single antibody that act as homing devices to match only one type of antigen (a protein on the surface of tumor cells that stimulates an immune system response). Scientists at NINDS and elsewhere are linking these antibodies to immunotoxins that search for tumor cells with a suitable antigen, bind to these tumor cells, and deliver the toxin, with minimal damage to surrounding normal cells. Additional approaches include attaching radioactive substances to antibodies, which act as targeting agents to deliver radiation to tumor cells.
Gene therapy (also called gene transfer) aims to deliver a suicide gene to tumor cells. It can also be used to boost the immune system. Genes whose activity can be influenced to kill cells are integrated into a virus that can cross the blood-brain barrier (a complex network of blood vessels and cells that filter blood to reach the CNS) and travel to tumors. The delivery methods under research include viruses and stem cells. Gene therapy may be an important adjunct therapy for patients who do not respond well to other treatments.
Scientists are testing the effectiveness of vaccine therapy for various CNS tumors. Vaccine therapy strengthens the immune response by inserting antigens that the body will attack. Some vaccines target specific antigens, while others use entire tumor cells to make vaccines, hoping to target some of the antigens the tumor may express. Research has shown vaccines can be genetically engineered with tumor antigens and injected into the body to induce an immune response, which increases the attack against antigens expressed on the surface of tumor cells. Experimental CNS tumor vaccines include those designed to stimulate the body’s immune response to certain proteins or antigens, and dendritic cell vaccines (in which blood cells are taken from the body, processed in the laboratory and given back to the patient to break down proteins outside the tumor cells into smaller parts, which increases targeting by immune cells).
Findings from an NIH-sponsored study on the development and treatment of adult CNS tumors suggest the immune system and, potentially, infection with cytomegaloviruses may play an vital role in the risk and prognosis of certain tumor types. Repeated stimulation of the immune system to fight the herpes virus may serve as a tumor promotion factor. Scientists hope to identify immune factors and develop targeted immunotherapy for the disease.
Targeted therapy uses a variety of 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 specially designed therapies — involving a combination of targeted agents — to treat tumors based on their genetic makeup. In particular, molecularly targeted drugs look for molecular and cellular changes that turn normal cells into cancer. Many cancer-targeted therapies are being tested in animals for use alone or in combination with other cancer treatments, such as chemotherapy. Researchers hope to find tumor-specific cellular or molecular pathways that can be used to improve drug delivery and find ways to identify patients who may benefit from combined therapy. Targeted therapies include oncogene, growth factors, and molecules aimed at blocking gene activity.
Growth factors often regulate normal cell growth. Growth factors are released from surrounding cells or tissues. Cancer cells can secrete growth factors or respond to them, allowing them to divide out of control. A number of tumor growth factors have been identified, including those that stimulate the growth of nerve tissue and stimulate blood vessels to grow (a process called angiogenesis). Researchers continue to identify and develop agents that can block these factors.
Anti-angiogenic compounds block blood vessel growth and the flow of nutrients and oxygen to tumors, and may also inhibit cell signaling and stop tumor cells from spreading elsewhere in the body. Clinical trials have shown that anti-angiogenesis can improve outcomes for glioblastoma multiforme tumors that recur after initial treatment with radiation and chemotherapy. More than a dozen of these compounds have been identified, including bevacizumab, interferon, and endostatin. Researchers are studying a combination of anti-angiogenic and radiation or chemotherapy to treat newly diagnosed brain tumors. Another study is testing angiogenic inhibitors that have had positive results in adults and children with primary CNS tumors and in patients with tumors that have not responded well to other tumor treatments.
Oncogenes transform genes involved in cell growth and cause normal cells to divide uncontrollably and become malignant, either through mutation or overexpression. Researchers have identified the specific events that lead to this mutation and developed diagnostic and therapeutic screening tools.
Certain enzymes involved in cell division or copying of genetic information can be overproduced in cancer cells, causing gene mutations and uncontrolled cell growth. Several different types of kinase inhibitors — proteins that inhibit growth-signaling enzymes without damaging normal cells — have been identified and approved for cancer treatment. Scientists are testing protein-level kinase inhibitors to see if 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 recurrent or difficult to treat tumors.
Antisense oligonucleotide technology uses short fragments of nucleic acid molecules to block gene expression in certain cells and prevent tumor growth. In contrast to gene therapy, antisense oligonucleotide technology does not replace or replace genetic material but inhibits the expression of selected targets. This technology (also known as interference RNA, siRNA, or shRNA) could 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) —the natural molecules that regulate gene expression and are involved in the formation and development of tumor stem cells. The researchers are using miRNAs to turn off tumor stem cell activity. Researchers are studying miRNA as a possible diagnostic and therapeutic strategy for brain tumors and other forms of cancer.
Biomarkers are molecules or other substances in blood or tissue that can be used to diagnose or monitor certain disorders, among other functions. When cells become cancerous, they can release unique proteins and other molecules into the body that scientists use to speed up diagnosis and treatment. Several biomarkers of CNS tumors have been identified, such as the epithelial growth factor receptor (EGFR) gene. Researchers are continuing to search for additional clinical biomarkers of CNS tumors, to better assess the risk from environmental toxins and other possible causes, and monitor and predict outcome of CNS tumor treatment. Recent NINDS-funded research suggests that EGFR mutation analysis can be used to predict which tumors are most likely to respond to certain class of cancer-fighting drugs. Identifying biomarkers may also lead to the development of new models of disease and new therapies for tumor treatments.
Radiation therapy research includes 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. Areas of research explored include tomotherapy, boron nuclear capture therapy, liquid radiation therapy, and use of radiosensitizers.
Radiosensitizers are drugs that make rapidly dividing tumor tissue more susceptible to radiation. Early studies using radiosensitizers resulted in mixed results. Some trials have shown this drug may improve survival in certain patients, while other trials have found only a slight benefit. Scientists are now testing experimental drugs that increase the amount of oxygen released from the blood into tissues, making cancer cells more responsive to radiation and chemotherapy. Studies show a lack of oxygen in tumors 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 giving radiation via tomotherapy and seeing whether the side effects of long-term radiation therapy can be reduced.
Boron Neutron Capture Therapy (BNCT) is an experimental treatment that uses fission to kill tumor cells. Amino acids or other drugs containing boron are injected into patients, where they collect more easily in tumor cells than in regular tissue. The low-energy neutron beam is directed at the tumor from outside the body, causing the boron atoms to break apart (called a neutron capture) and send high amounts of energy to the cancer cells. Radiation damage to surrounding cells is very small. BNCT is being tested as a postoperative treatment for patients with certain head and neck tumors. If successful, BNCT could be used to treat children with brain tumors someday
Liquid radiation therapy is an experimental treatment that uses a balloon catheter to deliver internal radiation therapy to the cavity that remains after tumor surgery. The radioactive liquid is injected into the catheter and molds the balloon to the cavity’s edges. The liquid remains in the balloon for several days until the catheter is removed.
Chemotherapeutic drug research focuses on ways to better deliver drugs across the blood-brain barrier and to the site of the tumor. Since chemotherapy drugs work in different ways to stop tumor cells from dividing, some trials are testing whether giving more than one drug, and perhaps giving them in different ways (such as scheduled delivery and long-term, low-dose treatment), may kill more tumor cells. tumors without causing or reducing damaging side effects than present therapy. The researchers are examining different levels of chemotherapy 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. Areas of research include differentiating drugs, osmotic blood-brain barrier disruption, and delivery of enhanced convection.
Differentiating drugs change dividing cells into non-dividing cells and can stop tumor growth. An early study using retinoids (made from vitamin A) as an independent treatment for certain tumors did not show a significant effect. Scientists are trying retinoids in combination with chemotherapy drugs or other medications to slow the growth of malignant gliomas.
Researchers are testing a variety of 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 or osmotic blood-brain barrier disruption uses certain drugs to open blood vessels throughout the brain. Scientists are currently studying whether certain chemotherapy drugs, when given with osmotic blood-brain barrier disruption, might be an effective way to kill cancer cells without harmful side effects.
The enhanced convection delivery sends a continuous and uniform flow of toxic drugs into the tumor via a catheter inserted during surgery. This drug delivery system, which passes through the blood-brain barrier, is being evaluated in children with recurrent brain cancer and in patients whose tumor location prevents its total surgical removal.
Repeated surgical resection has been shown to be beneficial for certain patients with recurrent malignant gliomas. Further research is underway to better define the potential benefits of surgery, including better response to biologic therapy and chemotherapy, improved quality of life, and longer-lasting 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 therapy. 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 this transplant in protecting blood cells in children with certain types of CNS tumors and in other patients with recurrent or difficult-to-treat CNS cancers who receive higher doses of chemotherapy.
Although many new approaches to treatment appear promising, it is important to remember that all potential therapies must withstand well-designed clinical trials, 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 rapidly evaluate new agents and may involve initial selection of patients based on molecular abnormalities in their tumors.
Previous research has resulted in improved tumor treatments and techniques for many patients with CNS tumors. Current research promises to yield further improvements. In the coming years, physicians and patients who have a CNS tumor can look forward to new, more effective, and less toxic forms of therapy developed through better molecular understanding of the unique features of CNS tumors.
Highlights on Brain Tumors
Do You Know the Symptoms?
Brain tumors are not like tumors in other parts of your body. Brain tumors have limited space for growth because it is enclosed within the bony skull. This means that the growing tumor may put pressure on vital parts of the brain and cause serious health problems. Learning about the possible symptoms of a brain tumor can help you know when to tell your doctor about these symptoms.
A tumor is an abnormal mass of cells that form lumps or growths. Most normal cells that become old or damaged will die and be replaced with new cells. However, it may not happen in some cases. New cells form when the body does not need them, and old, damaged cells do not die as they should. The extra cells may usually form tumors.
Tumors that start in the brain are called primary brain tumors. Primary brain tumors can affect people of all ages, including children. There are many different ways this tumor can form.
Cancer that has spread to the brain from other parts of the body is called a metastatic brain tumor. Metastatic brain tumors are more common to occur than primary tumors.
Primary and metastatic brain tumors may have the same symptoms. Symptoms mainly depend on the site of the tumor in the brain.
Symptoms of a brain tumor can be dramatic or subtle. Seizures are an example of a dramatic symptom. About 3 out of every 10 patients with a brain tumor are diagnosed after having a seizure.
Other symptoms are less subtle. For example, you may experience memory problems or weakness on one side of your body. Before symptoms develop, you may not know you have a brain tumor.
If you have symptoms that suggest a brain tumor, inform your doctor right away. Your doctor will perform a physical exam and ask about your personal and family medical history. You may require additional tests. Tumors can be detected with imaging testing procedures such as MRI or CT scan.
Researchers are constantly looking for improved ways to detect and treat brain tumors. Treatment differs depending on the type and location of the tumor. Treatment may involve surgery, radiation (high-energy beams aimed at the tumor), or drugs that kill or block the growth of cancer cells.
Typically, treatment for a brain tumor requires a team of healthcare professionals. This may include surgeons, oncologists, nutritionists, nurses, and mental health professionals. Not only for treating the tumor, but they also will help improve the patient’s quality of life.