What Are Brain and Spinal Cord Tumors in Children?
Brain tumors are masses of abnormal cells that have grown out-of-control. In most other parts of the body, it is critically important to distinguish benign (noncancerous) tumors from malignant (cancerous) ones. Benign tumors are almost never life threatening. The main reason cancers are so dangerous is because they can spread throughout the body. Most brain cancers can spread through the brain tissue but rarely spread to other areas of the body. Even so-called “benign” tumors are can, as they grow, compress brain tissue, causing damage that is often disabling and sometimes fatal. For this reason, doctors usually speak of "brain tumors" rather than "brain cancers." The major distinction is how readily they spread through the rest of the brain central nervous system and whether they can be removed and not come back.
The central nervous system is the medical name for the brain and spinal cord. Central nervous system tumors of adults and children often form in different areas, develop from different cell types, and may have a different outlook and treatment. This document refers to children's tumors.
The brain is the center of thought, feeling, memory, speech, vision, hearing, movement, and much more. The spinal cord and special nerves in the head called cranial nerves carry messages between the brain and the rest of the body. These messages tell our muscles how to move, transmit information gathered by our senses, and help coordinate our internal organs. The brain is located within and protected by the skull. Likewise, the spinal cord is protected by the bones of the spinal column. The brain and spinal cord are surrounded and cushioned by a special fluid, called cerebrospinal fluid. Cerebrospinal fluid is produced by the choroid plexus, which is located in cavities within the brain called ventricles. The ventricles as well as the spaces around the brain and spinal cord are filled with cerebrospinal fluid.
Parts of the Brain and Spinal Cord
The brain and spinal cord are the 2 main parts of the central nervous system.
The main areas of the brain include the cerebral hemispheres, cerebellum, and brain stem. Each of these parts has a special purpose. Tumors of different parts of the central nervous system disrupt different functions and cause different symptoms. Any disease involving that particular location within the brain can cause these symptoms, and they do not necessarily mean a brain tumor is present. Also, tumors in different areas of the central nervous system may be treated differently and have a different prognosis (outlook for survival). In very young children, less than 3 years of age, it’s often hard to tell which part of the brain is affected during its early development. Very young children may not have the usual symptomns coming from that part of the brain involved as would be seen in adults. In this age group the only symptoms may be nonspecific and include irritability, crying, poor feeding, or vomiting.
The 2 cerebral hemispheres control reasoning, thought, emotion, and language. They are also responsible for your planned muscle movements (throwing a ball, walking, chewing, etc.) and for taking in sensory information such as vision, hearing, smell, touch, and pain.
The symptoms caused by a tumor in a cerebral hemisphere depend on the part of the hemisphere in which the tumor arises. Common symptoms include:
- seizures
- trouble speaking
- a change of mood such as depression
- a change in personality
- numbness, weakness or paralysis of part of the body
- changes in vision, hearing, and sensation
The cerebellum controls coordination of movement. Tumors of the cerebellum cause difficulty with coordination in walking, difficulty with fine movements of arms and legs, and changes in rhythm of speech.
The brain stem contains bundles of very long nerve fibers (axons) that carry signals controlling muscles and sensation or feeling from the cerebrum to and from the rest the body. In addition, most cranial nerves (which carry signals to and from the face, eyes, tongue, and mouth) start in the brain stem. Special centers in the brain stem also control breathing and the beating of the heart.
Tumors in this critical area of the brain may cause weakness, stiff muscles, or problems with sensation, hearing, facial movement, and swallowing. Double vision is a common early symptom of brain stem tumors, as are problems with coordination in walking. Because tumors of the brain stem often intermingle with normal nerve cells and the brain stem is so essential for life, it may not be possible to surgically remove these tumors from the brain stem.
The spinal cord, like the brain stem, contains bundles of very long axons (wire-like extensions) that carry signals controlling muscles, sensation or feeling, and bladder and bowel control. Spinal cord tumors may cause weakness, paralysis, or numbness. Because the spinal cord is such a narrow structure, tumors arising within it usually cause symptoms involving both sides of the body (for example, weakness or numbness of both legs). This is different than tumors of the brain, which usually affect only one side of the body. Moreover, most tumors of the spinal cord arise below the neck after nerves to the arms have branched off the spinal cord, so that only lower body functions – bowel, bladder, or leg – are affected.
Tumors may also arise from cranial nerves. The most common cranial nerve tumor in children is optic glioma, a tumor of the optic nerve (the optic nerve is actually an extension of brain tissue to the eye) causing blindness. Tumors arising from other cranial nerves may cause hearing loss (acoustic nerve) in one or both ears, facial paralysis (facial nerve), or facial numbness or pain (trigeminal nerve). Tumors arising in the nerves of the peripheral nervous system (parts of the nervous system other than the brain and spinal cord) generally cause pain, weakness,and/or loss of sensation in the area served by that nerve. They can also weaken the muscles controlled by that nerve.
Types of Cells and Tissues in the Brain and Spinal Cord
The brain consists of different kinds of tissues and cells. Different types of tumors can start in these different cell and tissue types. These different types of tumors have varying outlooks for survival and may be treated differently.
Neurons: These are the most important cells within the brain. They send signals through the axons. Axons may be very short (in the brain) or 2 to 3 feet long (in the spinal cord). Electric signals carried by neurons determine thought, memory, emotion, speech, muscle movement, and just about everything else that the brain and spinal cord do. Unlike many other types of cells that can grow and divide to repair damage from injury or disease, neurons quit dividing about 1 year after birth (with a few exceptions). Neurons do not usually form tumors, but they are damaged by tumors that start nearby.
Glial cells: Most brain and spinal cord tumors develop from glial cells. There are 3 types of glial cells – astrocytes, oligodendrocytes, and ependymal cells. Tumors of glial cells are sometimes referred to as a group and called gliomas. A fourth cell type called microglia is part of the immune system and is not truly glial in origin. Normal glial cells grow and divide very slowly. Glial cells are the supporting cells of the brain and continue to increase in number until the child is 5 years of age. At this time, the brain reaches its maximum size and will be the same size throughout one’s lifetime.
- Astrocytes help support and nourish neurons. When the brain is injured, astrocytes form scar tissue that helps repair the damage.
- Oligodendrocytes make myelin, a substance that surrounds and insulates axons of the brain and spinal cord. This allows oligodendrocytes to help neurons transmit electric signals through axons.
- Ependymal cells line the ventricles within the central part of the brain and form part of the pathway through which cerebrospinal fluid travels.
- Microglia represent 10% to 20% of the total population of glial cells in the brain. They are the immune (infection fighting) cells of the central nervous system.
Neuroectodermal cells: These are primitive cells that are probably the remains of embryonic cells and are found throughout the brain. The most common tumor that comes from these cells is the medulloblastoma, which arises in the cerebellum.
Meninges: These are specialized tissues that line the cerebrospinal fluid-filled spaces surrounding the brain and spinal cord. The meninges help form the spaces through which cerebrospinal fluid travels.
Choroid plexus: The choroids plexus is the area of the brain within the ventricles that makes cerebrospinal fluid, which nourishes and protects the brain.
Pituitary gland and hypothalamus: The pituitary is a gland found at the base of the brain. The hypothalamus is a part of the brain next to the pituitary gland. Both of these tissues help regulate the activity of several other glands. For example, they control the production of thyroid hormone by the thyroid gland, the production and release of milk by the breasts, and the production of male or female hormones by the testicles or ovaries. They also produce growth hormone, which stimulates body growth, and vasopressin, which regulates water balance by the kidneys.
The growth of tumors in or near the pituitary or hypothalamus, as well as surgery and/or radiation therapy in this area, can interfere with these functions. Consequently, a child may have low levels of one or more hormones and may need hormone treatments to correct any hormone deficiency.
Pineal gland: The pineal gland is not strictly part of the brain. It is, in fact, an endocrine gland that sits between the cerebral hemispheres. Its function is probably to make melatonin, a hormone that responds to changes in light.
Blood-brain barrier: Unlike most other organs, there is a barrier between the blood and the tissues of the central nervous system (brain and spinal cord) that keeps many drugs from getting into the brain, including most chemotherapy drugs that are used to kill cancer cells. However, some chemotherapy drugs can cross the blood-brain barrier to treat some malignant brain tumors.
Types of Brain and Spinal Cord Tumors
Sometimes brain tumors are found not to have started in the brain but rather to have spread, or metastasized, from some other part of the body. Tumors that start in other organs and then spread to the brain are called metastatic brain tumors and those that start in the brain are called primary brain tumors. This is important because metastatic and primary brain tumors are usually treated differently.
In children, metastatic tumors to the brain are much less common than primary brain tumors. Unlike other cancerous tumors, tumors arising within the brain or spinal cord rarely metastasize to distant organs. They cause damage because they spread locally and destroy normal tissue where they arise. This document only covers primary brain tumors.
Gliomas: This is not a specific type of cancer. Glioma is a general category that includes glioblastoma multiforme, primitive neuroectodermal tumors, anaplastic astrocytoma, astrocytomas, oligodendrogliomas, ependymomas, brain stem gliomas and optic gliomas. Because this word is often used in discussing brain tumors, it is defined here in an attempt to reduce confusion with it.
Tumors can form in any type of tissue or cell within the brain or spinal cord. Some tumors contain a mixture of cell types. The most common brain and spinal cord tumors of children are astrocytomas. The second most common are primitive neuroectodermal tumors (23%), and the third most common are other kinds of gliomas such as brain stem gliomas (15%). Ependymomas are the fourth most common at 9%. All the others are fairly uncommon and account for only 3%.
Astrocytoma: Most tumors that arise within the brain itself start in brain cells called astrocytes, a kind of glial cell. These tumors are called astrocytomas. About half of all childhood brain tumors are astrocytomas. Many astrocytomas cannot be cured because they spread widely throughout, and intermingle with, the normal brain tissue. They are called infiltrating astrocytomas. Sometimes infiltrating astrocytomas spread along the cerebrospinal fluid pathways. But it is very rare for them to spread outside of the brain or spinal cord.
Infiltrating astrocytomas are classified as low grade, intermediate grade, or high grade. A pathologist (a doctor specializing in the diagnosis of diseases by laboratory tests) will grade them based on how the cells from a biopsy specimen (sample of the tumor) look under the microscope. Low-grade astrocytomas are the slowest growing and the most common type of astrocytoma in children. Intermediate-grade astrocytomas, or anaplastic astrocytomas, grow at a moderate rate. The highest-grade astrocytomas, glioblastomas, are the fastest growing.
There are some special types of astrocytomas that tend to have a particularly good prognosis. These are juvenile pilocytic astrocytomas and subependymal giant cell astrocytomas.
- Juvenile pilocytic astrocytomas most commonly occur in the cerebellum but also occur in the optic nerve, hypothalamus, brain, or other areas.
- Subependymal giant cell astrocytomas occur in the ventricles and are almost always associated with tuberous sclerosis (an inherited condition which may also cause epilepsy, mental retardation, and tumors of the skin and kidneys).
Certain tumors possibly of mixed glial and neuronal origin that occur in children and young adults and rarely in older adults also have a good prognosis. One such tumor is the pleomorphic xanthoastrocytoma and another is the dysembryoplastic neuroepithelial tumor. Although they appear malignant under the microscope, these tumors are relatively benign and most are cured by surgery alone.
Oligodendrogliomas: These tumors start in brain glial cells called oligodendrocytes. They spread or infiltrate in a manner similar to astrocytomas and, in most cases, cannot be completely removed by surgery. A small number of oligodendrogliomas, however, are associated with long-term survival of 30 or 40 years. Oligodendrogliomas may spread along the cerebrospinal fluid pathways but rarely spread outside the brain or spinal cord.
Optic Glioma: Optic gliomas are low-grade tumors of childhood and are frequently associated with an inherited condition called neurofibromatosis-type 1. These tumors, which arise from the optic nerve, can sometimes be treated successfully by surgery. At other times radiation therapy or chemotherapy may be required. The tumors are rarely lethal but may cause substantial visual loss.
Ganglioglioma: This tumor contains both mature neurons and glial cells. It has a high rate of cure by surgery alone or surgery combined with radiation therapy.
Primitive neuroectodermal tumors: Almost one fourth of brain tumors in children are of this type. They are rare in adults. When these arise in the cerebellum, they are called medulloblastomas. They are fast-growing tumors that can spread along the spinal cord and meninges but can be treated. Up to 50% of cases are cured by surgery and radiation therapy, sometimes with added chemotherapy. About 15% of childhood brain tumors are medulloblastomas.
Primitive neuroectodermal tumors are called pineoblastomas when they occur in the pineal gland. Other forms of primitive neuroectodermal tumors are all rapidly growing tumors that frequently spread throughout the cerebrospinal fluid pathways. The outlook for pineoblastomas is not as favorable as for medulloblastomas.
Ependymomas: Almost 10% of brain tumors in children are ependymomas. These tumors arise from the ependymal cells that line the ventricles or central canal of the spinal cord. Ependymomas may block the exit of cerebrospinal fluid from the ventricles causing the ventricle to become very large – a condition called hydrocephalus. Unlike astrocytomas and oligodendrogliomas, ependymomas usually do not spread or infiltrate into normal brain tissue. As a result, some but not all ependymomas can be removed and cured by surgery. Spinal cord ependymomas have the greatest chance of surgical cure. Ependymomas may spread along the cerebrospinal fluid pathways but do not spread outside the brain or spinal cord. Ependymomas represent about 9% of childhood brain tumors.
Choroid plexus tumors: These tumors arise in the choroid plexus within the ventricles of the brain. They are usually benign and cured by surgery (choroid plexus papillomas). However, they may also be malignant (choroid plexus carcinomas).
Craniopharyngioma: This type of tumor arises above the pituitary gland but below the brain itself. Most craniopharyngiomas are very close to the optic nerve, making surgical removal difficult, because of possible damage to the child’s vision. They may also compress the pituitary gland and the hypothalamus causing hormonal problems. Some are cured by surgery; others require radiation therapy.
Schwannoma (neurilemoma): This type of tumor starts in Schwann cells that surround and insulate cranial nerves and other nerves. Schwannomas are usually benign tumors that often form near the cerebellum and in the cranial nerve, which is responsible for hearing and balance. They also arise from spinal nerves after they have left the spinal cord and can compress the spinal cord causing weakness, sensory loss, and bowel and bladder problems. These tumors are rare in children and when present in this age group, particularly if there is more than one, might suggest an inherited familial tumor syndrome such as neurofibromatosis.
Meningioma: This type of tumor arises from the meninges, the tissue that surrounds the outer part of the brain and spinal cord. Meningiomas cause symptoms by pressing on the brain or spinal cord. Meningiomas are much less common in children than in adults.
Meningiomas are benign and are usually cured by surgery. Some meningiomas, however, are located dangerously close to vital structures within the brain and cannot be cured by surgery. Meningiosarcomas are rare but very malignant (cancerous) tumors that may come back many times after surgery or, in rare occasions, spread to other parts of the body.
Chordoma: This tumor starts in the bone at the back of the skull or at the lower end of the spinal column. Chordomas may come back many times over a period of 10 to 20 years causing progressive neurologic damage and deterioration. But they usually do not spread or metastasize to other organs.
Germ cell tumors: Germ cell tumors develop from germ cells that normally form eggs in women and sperm in men. During normal embryonic and fetal development, germ cells migrate to the ovaries or testicles and develop into eggs or sperm cells. Sometimes, however, a few germ cells may not migrate properly and end up in abnormal locations such as the brain. They may then develop into germ cell tumors similar to those that can form in the ovaries or testicles.
Germ cell tumors of the nervous system usually occur in children, most often in the pineal gland or above the pituitary gland. The most common germ cell tumor of the nervous system is the germinoma, which can be cured by radiation therapy and possibly chemotherapy in almost all cases. Other tumors of germ cell origin such as choriocarcinoma or yolk sac tumors are rarely cured by surgery. Both radiation therapy and chemotherapy are used in their treatment and in some cases this may not control the tumor completely. Germ cell tumors can sometimes be diagnosed without a biopsy by measuring certain chemicals in the cerebrospinal fluid or blood.
Neuroblastoma: Another kind of nerve cell tumor, which is not a brain tumor, is called neuroblastoma. This is the third most common cancer in children. Neuroblastomas rarely develop in the brain or spinal cord; most develop from nerve cells inside the abdomen or chest. This type of cancer is most commonly diagnosed during early infancy.
What Are the Differences Between Cancers in Adults and Children?
| Detailed Guide: Brain / CNS Tumors in Children |
| What Are the Differences Between Cancers in Adults and Children? |
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Children and adolescents with brain and spinal cord tumors and their families have special needs that can be best met by cancer centers for children and adolescents working closely with the child's primary care physician. Treatment in specialized centers takes advantage of a team of specialists who know the differences between cancers that occur in adults compared to those that occur in children and adolescents, as well as the unique needs of children and adolescents with cancers. This team should include pediatric oncologists, neurosurgeons, radiation oncologists, neuroradiologists, neurologists, neuropathologists, endocrinologists, psychologists, pediatric oncology nurses, and nurse practitioners.
The treatment of cancer in children and adolescents also involves many professionals other than nurses and doctors. Children's cancer centers have social workers, child life specialists, nutritionists, rehabilitation and physical therapists, and educators who can support and educate the entire family. Since the 1960s, most children with cancer have been treated at specialized centers designed for children.
Most children with cancer in the United States are treated at a center that is a member of the Children's Oncology Group (COG). All of these centers are associated with a university or children's hospital.
Do We Know What Causes Brain And Spinal Cord Tumors in Children?
The cause of central nervous system tumors is not fully understood. Nevertheless, researchers are making progress toward understanding some of the chemical changes that occur inside normal brain cells that turn them into brain tumors.
Brain tumors, like other tumors, are caused by abnormal changes in the genes. Genes, the "chemical building blocks of life," are made of DNA and are found in all cells within the body. The genes that we inherit from our parents make us who we are and are the reason that we are often very similar to our parents. In addition to determining how we look, genes also control every aspect of our body's metabolism. This is why abnormal genes can cause some diseases. Abnormalities of genes are called mutations. Gene mutations that cause some diseases (including some tumors) can be inherited.
Recently, researchers have found that gene mutations that cause some rare inherited syndromes (like neurofibromatosis, tuberous sclerosis, Li-Fraumeni, and Von Hippel- Lindau) are associated with an increased risk of developing some central nervous system tumors. For example, the Li-Fraumeni syndrome is caused by mutation of the p53 tumor suppressor gene. Normally, this gene prevents cells with damaged DNA from growing. When mutated, it increases the risk of developing breast cancer, soft tissue sarcomas, and brain tumors (particularly astrocytomas).
Some other gene mutations involved in forming brain and spinal cord tumors that are not inherited are also known. Research into these mutations has led to some experimental treatments for central nervous system tumors that, in the future, may be further refined.
It is not known why people without inherited tumor-causing mutations develop mutations in cells of their central nervous system. Most risk factors for cancer somehow damage genes. For example, cigarette smoke is a risk factor for lung cancer and several other cancers because it contains chemicals that can damage genes. The brain is relatively protected from cigarette smoke and other cancer-causing chemicals that we all breathe or eat. The vast majority of brain tumors happen for no apparent reason and are not associated with anything which the child did or didn't do, or anything that the child was exposed to in the environment.
Can Brain and Spinal Cord Tumors in Children Be Found Early?
No blood test or other screening examination is currently available to detect brain tumors at an early stage. In most cases, survival of patients with brain tumors depends on the type of tumor and its location, not how early it is detected.
For most tumors of the brain or spinal cord there is little evidence that early diagnosis and treatment increases the chance for survival.
How Are Brain and Spinal Cord Tumors in Children Treated?
This information represents the views of the doctors and nurses serving on the American Cancer Society's Cancer Information Database Editorial Board. These views are based on their interpretation of studies published in medical journals, as well as their own professional experience.
The treatment information in this document is not official policy of the Society and is not intended as medical advice to replace the expertise and judgment of your cancer care team. It is intended to help you and your family make informed decisions, together with your doctor.
Your doctor may have reasons for suggesting a treatment plan different from these general treatment options. Don't hesitate to ask him or her questions about your treatment options.
Children with central nervous system tumors may be treated by surgery, radiation therapy, and/or chemotherapy. Treatment is different for different kinds of tumors. Each child's treatment must be approached individually to give the child the best chance of cure. Long-term side effects of the treatment must also be considered. Because of this, children under 3 years old are usually not given radiation therapy. Instead, the treatment relies mainly on removing the tumor by surgery and chemotherapy.
This approach is based on the desire to delay the need for radiation therapy, which can cause developmental delay and problems with intellectual development. Even in older children, however, radiation treatment can cause problems. Radiation oncologists (doctors specializing in treatment of tumors with radiation) try very hard to limit the amount of normal brain tissue that they treat.
Surgical Treatment of Brain and Spinal Cord Tumors
Surgery to remove the tumor: Generally, the first step in brain tumor treatment is for the neurosurgeon (a surgeon who specializes in operating on the brain and other parts of the nervous system) to remove as much of the tumor as he or she can. Surgery alone or combined with radiation therapy may cure many tumors, including some cerebellar astrocytomas, pleomorphic xanthoastrocytomas, dysembryoplastic neuroepithelial tumors, ependymomas, craniopharyngiomas, gangliogliomas, meningiomas, and some low-grade gliomas.
Children with infiltrating tumors, such as anaplastic astrocytomas or glioblastomas, are not cured by surgery. But surgery will reduce the amount of tumor that needs to be treated by radiation or chemotherapy, and this may improves the results of these treatments.
In addition, surgery may improve some of the symptoms caused by brain tumors, particularly those caused by a build up of pressure within the skull. These symptoms include headache, nausea, vomiting, and blurred vision. Surgery can also improve symptoms of epilepsy and make the seizures more controllable with medications.
Craniotomy is the most commonly performed surgery for removal of a brain tumor. The neurosurgeon makes an incision in the scalp and then removes a piece of bone to expose the area of brain over the tumor. Next the surgeon locates the tumor and removes as much as is safely possible. The surgeon is always careful to avoid damaging normal brain tissue. After removing the tumor, the surgeon replaces the bone and sews the skin together.
Surgery to place a shunt: Blockage of the cerebrospinal fluid flow can cause increased pressure inside the skull. This pressure can cause the symptoms noted above and may even cause permanent damage to the brain. To drain buildup of cerebrospinal fluid and lower the pressure, the neurosurgeon can place a plastic tube called a shunt. One end of the shunt is placed in the ventricle of the brain (which contains cerebrospinal fluid) and the other end is placed in the abdomen or, less often, the heart. Cerebrospinal flow is controlled by a valve placed along the tubing. The tube runs under the skin of the head, neck, and chest. Shunts may be temporary or permanent and may be placed before or after the surgery to remove the tumor.
Radiation Therapy of Brain and Spinal Cord Tumors
Children whose brain tumors are not completely curable by surgery are usually treated with radiation therapy. The exception to this is children younger than 3 years. Radiation from an external source focused precisely on the tumor is called external beam radiation. This is similar to a diagnostic x-ray except that the dose is much greater, each treatment lasts longer, and many treatments are given over a period of many weeks. Radiation may sometimes be given by placing radioactive material directly within the tumor. This is called interstitial radiotherapy or brachytherapy.
Because high doses of radiation therapy can damage a child's normal brain tissue, the radiation oncologist attempts to deliver high doses of radiation to the tumor with the lowest possible dose to normal surrounding brain areas.
Newer techniques such as 3-dimensional treatment planning (conformal radiation) and stereotactic radiosurgery (with a "gamma knife" or a linear accelerator) have been developed to spare normal tissue. At present, research is being conducted to determine if these techniques are superior to standard external beam radiation therapy. See the section, "What's New in Brain Cancer Research and Treatment?" for more information on this new type of radiation therapy.
If tests such as an MRI scan or lumbar puncture find the tumor has spread along the spinal cord covering, the meninges, and surrounding fluid, radiation may be given to the whole brain and spinal cord. Some tumors such as medulloblastoma or other primitive neuroectodermal tumors are assumed to always involve the cerebrospinal fluid and because of this, nearly always require craniospinal radiation.
Up to one half of all medulloblastomas and virtually all germinomas are cured by radiation therapy. Unfortunately, radiation does not cure most other brain tumors. If there is a minimal amount of the tumor remaining after surgery astrocytomas, oligodendrogliomas and ependymomas can sometimes be controlled (but usually not cured) by radiation therapy.
Radiation is more damaging to tumor cells than it is to normal cells. Nevertheless, normal brain tissue will be damaged by radiation. Rarely (in less than 5% of patients), a large mass of dead tissue forms at the site of an irradiated tumor. This occurs months to many years after radiation is given and is called radiation necrosis (necrosis means dead). In most cases the dead tissue includes both cancerous and noncancerous tissue. Occasionally, surgery is necessary to remove the necrotic tissue.
Children whose brains are treated with radiation may lose some brain function if large areas of the brain received radiation. This can include memory loss, personality changes, and trouble learning at school. Other symptoms would be seizures and slowed growth. There may also be other symptoms depending on the area of brain treated and how much radiation was given. These risks must be balanced against the risks of not using radiation and having less control of the tumor. Sometimes it is difficult to determine whether the brain damage was caused by the tumor, the surgery, the radiation therapy, or a combination of all these. Researchers are continually testing lower doses of radiation to see if these doses can be as effective without as much brain damage.
Radiation can damage genes. As a result, radiation therapy is associated with a very small risk of developing a second cancer in the radiation field – for example, a bone cancer in the skull – usually many years after the radiation is given. This small risk should not prevent children who need radiation from getting treatment. More importantly, parents should continue close follow-up with their child's doctors so that early intervention is possible if problems arise.
Because normal brain cells grow rapidly within the first several years of life, radiation therapy is often postponed if your child is younger than 3 years old to avoid damage that might severely impair his or her future intellectual growth. This delay needs to be balanced with the risk of tumor regrowth. Early radiation therapy may be lifesaving. It is important that you talk with your child’s doctor about the risks and benefits of treatment.
During the course of radiation therapy, some children may become irritable and fatigued. Nausea, vomiting, and headache are unusual side effects of radiation therapy. Spinal radiation can cause nausea and vomiting more often than brain radiation. Some weeks after radiation therapy, children may become drowsy or neurologic symptoms may appear to worsen. This phenomenon is called the radiation somnolence syndrome or early-delayed radiation effect and usually passes after a few weeks. Sometimes dexamethasone (Decadron), a cortisone-like drug, can relieve the symptoms.
Chemotherapy of Brain and Spinal Cord Tumors
Chemotherapy uses anticancer drugs that are given into a vein intravenously (IV) or taken by mouth. In brain cancers, sometimes the drugs may be given directly into the ventricles or into the spinal canal below the spinal cord. These drugs, generally used only for high-grade tumors, may be given before or after surgery and radiation therapy. Some types of brain cancer, medulloblastoma for example, respond very well to chemotherapy. Chemotherapy, rather than radiation therapy, may be given to children 3 years and younger.
Some of the chemotherapy drugs used to treat children with brain tumors include:
- cyclophosphamide
- methotrexate
- lomustine (CCNU)
- carmustine (BCNU)
- etoposide
- thiotepa
- cisplatin
- carboplatin
- vincristine
- temozolomide
These drugs may be used alone or in various combinations, depending on the specific type of brain tumor.
Chemotherapy drugs kill cancer cells but will also damage normal cells. Your child's doctor will pay careful attention to avoiding or reducing the side effects of chemotherapy. These side effects depend on the type and dose of drugs given and the length of time they are taken. Drugs used in cancer chemotherapy specifically attack cells that are rapidly dividing. These drugs are effective because cancer cells spend more of their time dividing and reproducing than normal cells do.
However, there are some normal tissues such as the bone marrow, the lining of the mouth and intestines, and the hair follicles that also grow rapidly to replace cells that wear out. These rapidly growing cells are the ones most likely to be affected by chemotherapy.
As a result, your child may have hair loss, mouth sores, lowered resistance to infection (due to low white blood cell counts), easy bruising or bleeding (due to low blood platelets), and anemia (due to low red blood cells). Loss of appetite, nausea, and vomiting result in part from damage to intestinal cells, but effects of certain drugs on areas of the brain controlling appetite and vomiting also contribute to these problems. Fatigue may also occur but the cause of the fatigue is not clearly understood. These side effects are temporary and usually go away after treatment is finished.
Cisplatin and carboplatin can also cause kidney damage and hearing loss. Your doctor will check your child's renal function and hearing periodically to prevent excessive damage if he or she is given these drugs. Some of these side effects may persist after treatment is stopped.
If your child has side effects, your cancer care team can suggest steps to ease them. For example, drugs can be given along with the chemotherapy to prevent or reduce nausea and vomiting.
