The brain is the center of thought, memory, emotion, and speech, as well as the coordinator of the body’s voluntary and involuntary actions and processes. A network of nerves located in the brain itself and in the spinal cord exchanges 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 soft, spongy mass of brain tissue is located in the head and protected by the bones of the skull and three thin membranes called meninges. Watery fluid called cerebrospinal fluid cushions the brain. This fluid flows through spaces between the meninges and through spaces within the brain called ventricles. The brain and spinal cord compose the central nervous system. The brain and spinal cord have a complex structure that includes many cell types and tissues; consequently, there are over 50 types of tumors that start in the central nervous system (CNS). Brain and spinal cord tumors vary greatly in clinical behavior, outlook, and treatment. The American Cancer Society estimates about 20,000 new diagnoses of CNS tumors per year in the United States.
The majority of brain tumors are secondary tumors of cancers that started in a different organ and metastasized to the brain. Secondary tumors are treated differently than primary brain tumors, and the information about them should be found under the primary site. Information sources about CNS tumors focus only on tumors that started in the brain or spinal cord.
Primary brain tumors
Most primary brain tumors are not associated with any specific risk factor. A very small number of tumors are the result of radiation to the head that was given as treatment for a previous cancer. Other environmental factors such as exposure to certain chemicals or to cellular phones have been suggested as risk factors, but studies have not shown a clear connection. Immune system disorders, including AIDS (acquired immune deficiency syndrome), increase the risk for lymphoma of the brain or spinal cord. Information about CNS lymphoma can be found in either the CNS tumors or lymphoma information sources.
There are approximately 50 types of primary CNS tumors. About 35% of them are astrocytomas that start in brain cells called astrocytes. Most astro-cytomas cannot be cured because they spread widely throughout the surrounding normal brain tissue. About two-thirds of astrocytomas are glioblastoma multiform tumors that grow and spread very quickly. Intermediate-grade astrocytomas, or anaplastic astrocytomas, grow at a moderate rate, and low grade astrocytomas are the slowest growing. A few rare types of astrocytoma
have a better prognosis than the ones mentioned above.
Other types of Primary CNS tumors
Other types of primary CNS tumors are oligodendrogliomas, ependymomas, angliogliomas, schwannomas, and meduloblastomas. The term glioma is a general category that includes astrocytomas, oligodendrogliomas, and ependymomas.
Meningiomas, which originate in the meninges tissue surrounding the outer part of the brain and spinal cord, make up about 25% of all brain tumors and the majority of spinal cord tumors. Most meningiomas (about 85%) are benign and can be cured by surgery. Some meningiomas, however, are located dangerously close to vital structures within the brain and cannot be completely removed by surgery. Meningiomas do not metastasize beyond the CNS.
The first step in treating CNS tumors is usually surgery. Surgeons who operate in this delicate area require additional training in the subspecialty of neurosurgery. Cure is possible if the tumor is completely removed by surgery, but oftentimes a complete removal is not possible because of the tumor’s proximity to structures that control essential functions. In some cases it is even impossible to perform a biopsy because the potential for damage is greater than the benefit of knowing the exact histology of the tumor.
The surgery to open the skull and enable access to the brain is called craniotomy. Another procedure sometimes required is the placement of a shunt to bypass blockage in the flow of cerebrospinal fluid. Some tumors may cause an obstruction to the flow of cerebrospinal fluid, and the excess fluid may increase the pressure in the brain and cause severe symptoms or even death.
Most brain tumor patients are also treated by radiation either as adjuvant therapy or as the main therapy if surgery is not feasible. Radiation to the brain is delivered by several methods, including stereotactic radio-surgery. With this method narrow, high-dose beams of radiation are directed at the tumor while minimizing radiation delivered to normal brain tissue.
Chemotherapy is less effective against CNS cancers because of difficulty penetrating through the blood-brain barrier. The blood-brain barrier is a system of thin membranes that filter chemical molecules from the blood, including many drugs, in order to protect the sensitive brain tissue.
There is controversy regarding which anticancer drugs are able to penetrate the blood-brain barrier; however, some chemotherapy drugs have been shown
to have activity against brain tumors. Researchers are working on developing methods to bypass the blood-brain barrier. One such method is implantation of dissolvable wafers that are saturated with chemotherapy at the tumor site during surgery.
A large number of brain tumor patients are treated with steroids to reduce swelling and inflammation in the brain. Some patients are also treated with drugs that prevent seizures. Tumors in the brain and spinal cord and their treatment may cause difficulties in speech, movement, memory, and cognitive ability.
Rehabilitative services such as speech, physical, and occupational therapy can greatly improve or even restore function. Survivors and their families may need to adjust to life with certain limitations and changes in their employment and social environments.
American Brain Tumor Association. Access at: www.abta.org
This organization offers information and support services for people diagnosed with brain tumors. The “Tumor Information” section offers tumor-specific information as well as Adobe Acrobat (.pdf) files of two premier publications: A Primer of Brain Tumors: A Patient’s Reference Manual and Dictionary for Brain Tumor Patients.
The Brain Tumor Society Online. Access at: www.tbts.org
This site is provided for the entire brain tumor community, from newly diagnosed patients to survivors, families, and health care professionals. The “Patients Resources” section provides detailed medical information including pathology, nutrition, and lay-language summaries of published professional articles. This site also includes information about support services for patients and families and downloadable files of brochures and fact sheets published by the Brain Tumor Society.
MuseHa Foundation For Brain Tumor Research Information. Clinica/ Trials Noteworthy Treatments for Drain Tumors. Access at: www.virtualtrials.com
At the heart of this site is a comprehensive database of clinical trials for brain tumors. The site also includes a 48-page brain tumor guide for the newly diagnosed, which is downloadable as an Adobe Acrobat (.pdf) file; lay-term summaries of published studies, medical news, an online dictionary, and many interactive features. The extensive video library featuring brain tumor experts discussing various treatments is especially interesting.
National Brain Tumor Foundation (NBTF). Access at: www.braintumor.org
This site presents information regarding treatment options and community resources for brain tumor patients and families. Features include a database of questions answered by health professionals, a link library arranged by topic, and a treatment center database. Adobe Acrobat (.pdf) publications such as fact sheets and brochures are available, including The Essential Guide to Brain Tumors, a comprehensive 80-page booklet that covers symptoms, treatments, brain anatomy, and survivorship.
This article was originally published on 7/12/2014 and last revision and update of it was 9/14/2015.