Brain and Spinal Cord Cancer
Description
Brain and spinal cord cancers are caused by out-of-control division and growth of abnormal brain and spinal cord cells. Typically, brain tumors infiltrate the normal structures of the brain leading to disruption of brain function. Most brain tumors in adults arise from the glial cells that serve as supportive cells of the brain (astrocytes and oligodendrocytes). Fewer brain tumors arise from the brain cells responsible for sending and receiving signals that control the activities of the body (neurons).
Symptoms
Based upon location of the tumor, brain and spinal cord tumors can cause a variety of symptoms, such as:
- Frequent headaches (often in the morning)
- Nausea and vomiting
- Mood and personality changes
- Compromised cognitive function
- Altered vision, hearing or speech
- Loss of coordination or difficulty walking, for example, tripping and falling
- Paralysis
- Seizures
- Tingling or numbness
- Incontinence
These symptoms as well as other abnormal physical and mental impairments often provide the first indicator of brain and spinal cord cancer. Other conditions could also cause these symptoms and should be evaluated by a medical professional.
Primary and Secondary Tumors
Primary brain tumors: tumors that arise from glial or neuronal cells in the brain and spinal cord
Secondary brain tumors: tumors that travel to the brain or spinal cord, usually via the bloodstream from an organ outside the brain. The common sites of origin for secondary tumors, or metastasis, are cancers that arise in the lung, breast, skin (melanoma), kidney and gastrointestinal sites such as colon or stomach.
Tumor Grading
Brain and spinal cord tumors are graded on a scale from I to IV.
- Grade I tumors generally grow slowly, are easier to distinguish from healthy tissue and can be treated by surgery alone. Generally, prognosis is related to grade, with grade I the best prognosis and grade IV tumors the worst. However, because of the complexity of the nervous system, many other factors figure into the prognosis for the individual patient with a brain tumor, especially patient age, size of tumor, location of tumor, and specific diagnosis of tumor type.
- Grade I tumors are also called "benign" tumors. Because both the brain and spinal cord are protected by bone (skull, backbone), even benign tumors can prove dangerous, as tumor growth can press on the underlying brain or spinal cord tissue and intensify pressure upon the brain and spinal cord. Surgical removal may be necessary, but a cure is often possible.
- Grade II tumors tend to infiltrate surrounding brain or spinal cord. Grade II tumors often can be treated surgically, but the tumor may not be removed entirely. Grade II tumors tend to recur.
- Grade III and grade IV primary brain tumors grow more rapidly and are considered "malignant" brain tumors. These tumors may require surgical removal, if the location makes that possible, or biopsy for confirmation of diagnosis. Surgery is often followed by radiation therapy and chemotherapy.
- Metastatic tumors to the brain are, by definition, grade IV tumors. Treatment varies depending on the individual patient, ranging from surgical removal to chemotherapy or radiotherapy. Some of these are treated with focused, single-dose radiation therapy (gamma knife) without surgery, if the patient already has a known cancer in the lung, breast, or other site that is responsible for the metastatic lesion.
How Common are Brain and Spinal Cord Cancers?
- In 2008, researchers estimate that approximately 21,800 primary brain or spinal cord cancers will be diagnosed among adults in the United States.
- While brain and spinal cord cancer cases only represent a small percentage of the total annual cancer diagnoses in the U.S. (1.3 percent of all cancers), approximately 13,000 people will likely die from brain and spinal cord cancer this year.
- Brain and spinal cord cancer is the second most common cancer type in children.
Types of Brain and Spinal Cord Tumors
Tumors have the potential to arise from any of the diverse cells and tissue types that normally occur within the brain or spinal cord; in some cases, tumors will develop from a combination of cell or tissue types. Knowing the exact type of tumor is critical for better understanding of the prognosis and treatment that will be required.
- Meningiomas: typically benign tumors which grow on the membrane network located on the surface of the brain and spinal column, known as the meninges.
- Are more frequently diagnosed in adults than children;
- Are the most common benign brain and spinal tumor;
- Push on underlying brain or spinal cord; often can be surgically removed completely.
- Gliomas: primary cancers of the brain. Gliomas arise from glial cells (astrocytes, oligodendrocytes and ependymal cells), the "maintenance cells" of the brain; 78 percent of all malignant brain tumors are gliomas.
- Astrocytomas: tumors form in the astrocytes, cells that provide support to brain cells and tissues
- Glioblastoma multiforme, a type of astrocytoma, is an extremely aggressive and prevalent form of adult brain cancer; a grade IV tumor
- Astrocytomas are the most common brain and spinal cord tumors in children; may be of variable grades I through III.
- Oligodendrogliomas: tumors located in the oligodendrocytes, cells that help to ensure the quality of the signaling between neurons in the brain; may be of variable grades I through III.
- Ependymomas: tumors located in the ependymal cells, cells that line the cavities of the brain and spinal cord and facilitate the movement of cerebrospinal fluid; may be of variable grades I through III.
- Additional brain and spinal cord cancers include:
- Chordoma: tumors occurring within the bone at the base of spinal cord or skull; push on critical structures of the nearby nervous system.
- Ganglioglioma: tumors containing both tumorous neurons and glial cells; often cause seizures; most are grade I.
- Medullablastomas: tumors occurring in the cerebellum, a brain region that helps to control body movement and balance; most common in children; all are malignant (grade IV) tumors.
- Schwannoma: tumor of Schwann cells, cells that provide insulation for the connections (axons) that run between cells (neurons) in the nervous system; almost all are benign (grade I) tumors.
Diagnosis
To identify a tumor, a patient will undergo several imaging tests. Most commonly, magnetic resonance imaging (MRI) and computed tomography (CT) are used to locate brain tumors.
If an imaging test indicates a high likelihood of a tumor, surgically removing and analyzing a piece of the tumor tissue through a technique called biopsy is the only way to make a definitive diagnosis of the type and severity (grade) of the tumor. The information obtained through a biopsy will influence the treatment a patient will receive.
Treatment Options
Brain tumors, especially those that are primary and of higher grades, are among the most difficult to treat. While surgery, radiation therapy and chemotherapy remain the mainstays of treatment for these cancers, they are far from perfect.
Surgery
Surgery is the most common treatment for most types of brain and spinal cord tumors and, frequently, the only treatment for benign grade I brain tumors; however, brain surgery may be difficult and risky depending upon the exact location of a tumor.
- Most cases of benign tumors can be cured by surgery alone, and require no other treatment
- It is often impossible to remove higher grade tumors (grade II, III or IV) completely, given that the tumor usually invades normal brain tissue near the edge of the tumor. Still, neurosurgeons often attempt to remove as much of the tumor as possible, which sometimes can relieve symptoms.
- Metastatic tumors, although grade IV, can often be surgically removed completely since they are better demarcated in the brain. Patients still need additional therapy to control the tumor in the primary site or other metastatic sites in the body, for example, the lung, breast, skin, kidney or colon.
Chemotherapy
Chemotherapy, or anti-cancer drug treatment, attempts to halt uncontrolled cell division of cancer by destroying all rapidly dividing cells.
- Although chemotherapy techniques wipe out cancer cells, many normal, rapidly dividing healthy cells are also killed by these treatments. The death of healthy cells causes undesirable side effects for cancer patients. To decrease harmful side effects of chemotherapy, researchers are working to develop ways to tailor anti-cancer drugs to destroy cancer cells alone.
- Improvements to chemotherapy drugs also involve developing drugs that are able to bypass the blood-brain barrier, the protective web of vessels on the outside of the brain that keeps large chemicals present in the blood from entering the brain.
Anti-cancer drugs can be taken by mouth, vein, or by placing dissolving drug wafers into brain tumors. Commonly prescribed chemotherapy drugs for brain and spinal cord cancers are:
- Temozolomide (Temodar®)
- Carmustine (BCNU®)
- Cisplatin (Platinol®)
Additional chemotherapy drugs that may be prescribed to children include:
- Cyclophosphamide (Cytoxan®)
- Methotrexate
- Etoposide
- Thiotepa
- Carboplatin
- Vincristine
- Lomustine (CeeNu®)
Other drugs being developed to treat brain cancer:
- Growth factor inhibitors: drugs that halt a tumor's ability to grow
- erlotinib (Tarceva®) and gefitinib (Iressa®)
- Angiogenesis inhibitors: drugs that prevent blood vessel growth, blocking tumors from accessing nutrients and oxygen
- Most angiogenesis inhibitors are still in clinical trials; however, early studies suggest that patients with brain tumors benefit from angiogenesis drug treatments
Radiation
Radiation therapy fights cancer by damaging cancer cells with a powerful blast of energy. While doctors attempt to direct the radiation dose to a specific region of tumor, the radiation oncologist cannot fully prevent some of the radiation from reaching normal, healthy cells of the body. As a result, radiation therapy may also kill healthy cells. New radiation techniques try to avoid damaging normal tissue while still destroying brain cancer cells.
- Stereotactic radiosurgery entails delivering a single high dose of radiation directly to the tumor and not the surrounding, healthy tissue.
- Radiosurgery can be delivered in one dose, or divided into small daily doses over a period of time.
- Three-dimensional conformal radiation therapy uses a computer to create a model of the tumor and to determine the best radiation beam size, angle and dose.
- Intensity-modulated radiation therapy varies the dose intensity of radiation, depending on the thickness of the tumor.
New Scientific Developments
Scientists continue to work hard to better understand the causes of brain and spinal cord cancers and ways to improve current treatments.
Because glioblastoma is the deadliest and fastest-growing brain tumor, as well as the single most common type of primary brain tumor in adults, ongoing clinical research trials specifically target ways to improve survival rates among patients with this type of cancer.
A number of research centers are testing novel agents, alone or in combination with popular chemotherapy drugs, that inhibit angiogenesis (blood vessel growth), cell proliferation and tumor cell migration. By selectively disrupting critical steps in the cell signaling pathway, more effective treatments for brain tumor patients may be possible in the future. Targeted therapies, which aim drugs at specific proteins or other molecules involved in the development of disease, may offer the best hope for brain cancer patients.
In an effort to design drugs that can cross the blood-brain barrier and kill brain cancer, some researchers have turned to nanotechnology. Recent reports suggest that nanoparticles may provide the method of transportation for chemotherapy aimed at brain cancer.
Currently, brain cancer vaccines, drugs that boost the body's immune system to recognize and mount an attack upon tumor cells, are in clinical trials. Recent studies suggest when brain cancer vaccines are combined with common chemotherapy drugs, patients with brain cancer may live longer.
Related AACR Press Releases
Researchers Use Poliovirus to Destroy Neuroblastoma Tumors in Mice
March 15, 2007
Cancer Stem Cells Spur Glioma Angiogenesis, Could Hold Key to Brain Tumor Therapy
August 15, 2006
Cancerous vs. Healthy Cells: Researchers Identify the Road to Success
April 5, 2006
Sources
American Cancer Society. Cancer Facts & Figures. Atlanta, American Cancer Society, 2008
1-800-ACS-2345
www.cancer.org
National Cancer Institute
1-800-4-CANCER
www.cancer.gov
American Brain Tumor Association
1-800-886-2282
http://hope.abta.org
Brain Tumor Society
1-800-770-8287
www.tbts.org
Last reviewed: July 17, 2008