Brain tumor treatment is complex - so the hospital and doctor you choose is critical. For example, research has shown that patients achieve better outcomes when they are treated at major medical centers that offer multidisciplinary expertise for treatment of serious medical conditions such as brain tumors.
The origins of brain tumors
Many experts believe that a brain tumor occurs when certain genes on the chromosomes of a cell become damaged and can no longer function properly. These genes normally regulate how often the cell divides (or if it divides at all) and repair genes that become defective. Among the genes they repair are those that tell a damaged cell that cannot repair itself to self-destruct.
Some people may be born with partial defects in one or more of these genes and environmental factors may lead to further damage. In other people, environmental factors may be the only cause of damage to the genes.
Once a cell is dividing too rapidly and cannot check its own growth, it can grow into a tumor. Once the cell grows, brain tumor symptoms may appear. If a tumor cell begins to grow, the body's immune system should detect the abnormal cell and destroy it. Many tumors, however, produce substances that block the immune system from recognizing the abnormal tumor cells. Over time, the tumor cells overpower all of the body's defenses against their growth.
As with other cells, brain tumor cells need oxygen and nutrients to survive. Cells normally receive nourishment from blood brought to the tissues by blood vessels. However, a rapidly growing tumor may need more oxygen and nutrients than the nearby blood vessels can provide. In response, tumors produce substances called "angiogenic factors," which stimulate the growth of new blood vessels (angiogenesis). These new blood vessels increase the supply of nutrients to the tumor, which allows it to control growing.
Classifications of brain tumors
A brain tumor is any mass or growth of abnormal cells occurring in the brain tissue, skull, supportive tissue around the brain, cranial nerves, or the pituitary or pineal gland.
Brain tumors are classified as primary or secondary. Primary brain tumors develop from brain tissue or the areas surrounding the brain. Secondary, or metastatic, brain tumors are tumors that form from cancer cells that start in another part of the body, such as the breast or lung, and travel to the brain, usually by way of the bloodstream. Secondary brain tumors are more common than primary brain tumors.
Specialists who diagnose and treat brain tumors
- Neuropathologist: A physician with special training and experience in analyzing microscopic changes in brain and related tissue.
- Diagnostic neuroradiologist: A physician with special training and expertise in interpreting X-rays or scans that show the location and size of a brain tumor.
- Medical oncologist: A physician with special training and experience in the medical treatment of cancer through the use of different types of drugs (chemotherapy).
- Neuro-oncologist: A physician with special training and experience in the medical treatment of brain tumors by means of drugs or chemotherapy. This physician provides follow-up care after treatment as well as addressing neurologic issues.
- Radiation oncologist: A physician with special training and experience in treating tumors by means of internal and external radiation.
- Interventional neuroradiologist: A physician with special training and experience in specialized, invasive diagnostic and therapeutic techniques for brain tumors.
- Surgical neuro-oncologist: A neurosurgeon with special training or experience in diagnosing or surgically removing tumors of the brain or central nervous system.
Diagnosing brain tumors
Brain tumors can be diagnosed using computer technology that images the brain. Computerized tomography (CT) uses a computer and X-rays to make a 2-D axial image of the brain. Magnetic resonance imaging (MRI) creates a brain and brain tumor image using magnetic fields and radio waves. Magnetic resonance spectroscopy (MRS) shows the chemical composition of the brain. Other imaging techniques that may be used to assist in the diagnosis and treatment of a tumor include functional magnetic resonance imaging (fMRI), digital subtraction angiography (DSA), magnetic resonance angiography (MRA), positron emission tomography (PET), and single photon electron computerized tomography (SPECT).
In addition to their usefulness at the time of initial diagnosis, these technologies may also allow early detection of a brain tumor recurrence, which facilitates earlier treatment.
Most patients with a brain tumor undergo a biopsy, the surgical removal of a tissue sample from the tumor, either alone or as part of the surgical removal of a tumor. A neuropathologist examines the sample under a microscope to confirm the diagnosis, classify the tumor more specifically by the type of cells it contains, determine how abnormal the tumor cells are (histologic grade) and determine how quickly it is growing. The subtle but critical differences in cells that the pathologist detects under the microscope are crucial in making the correct diagnosis, which is used in determining further testing and appropriate brain tumor treatment for each patient. Today, the microscopic examination of some tumors may be extended by testing for changes in certain chromosomes and the presence or absence of certain molecules in the tumor cells, which can influence treatment.
Primary brain tumors
A primary brain tumor may be malignant (cancerous brain tumor ) or nonmalignant (benign brain tumor).
The degree of a brain tumor's malignancy is often referred to by its histologic grade (from I to IV). While Grade I brain tumors are benign, Grade II-IV brain tumors have increasing degrees of malignant characteristic and behavior. Malignant brain tumors contain cancerous cells.
High-grade malignant brain tumors (Grade III-IV) grow rapidly and invade healthy tissue around them. These brain tumors eventually crowd out or destroy the normal cells and interfere with their function. High-grade malignant brain tumors are life-threatening.
Low-grade brain tumors (Grade II) are less malignant and tend to grow more slowly. These brain tumors may co-exist with normal cells. However, they can invade surrounding tissue, and may cause severe neurologic impairment, such as seizures, behavioral changes and memory loss.
Nonmalignant (benign) brain tumors do not contain cancer cells and do not spread. However, they can be located in a vital or sensitive area of the brain and interfere with critical functions. Common benign primary brain tumors include those of the coverings of the brain (meningiomas), those of the nerves (schwannomas) and those of the pituitary gland (pituitary adenomas).
The National Cancer Institute (NCI) of the National Institutes of Health (NIH) has dozens of classifications for brain tumors, based on where the tumors arise in the brain and their characteristic growth pattern. Each type of brain tumor has a different prognosis. There may be several recognized, effective treatments for any one type of brain tumor.
Secondary (Metastatic) brain tumors
Cancer cells from other areas of the body may eventually spread (metastasize) to the brain or spinal cord. These metastatic brain tumors occur in approximately 25% of cancer patients. Metastatic brain tumors are, by definition, cancerous and generally cause seizures or loss of critical brain function. Traditionally, the prognosis for patients with these brain tumors was bleak; people were expected to survive only several weeks after diagnosis. More aggressive surgical treatments, innovative radiation approaches and promising therapeutic agents can now lead to improved quality of life and survival that is measured in months to years for patients with metastatic brain tumors.
Pediatric brain tumors
Central nervous system brain tumors are the most common type of solid tumors in children. Though the prognosis for pediatric brain tumors has dramatically increased in the last 20 years, treatment still poses significant challenges to the child and family and requires the comprehensive care of experts with special training.
Pediatric brain tumors in children often arise from tissues that are different from those most commonly affected in adults. In addition, some of the treatments that are tolerated by an adult's brain can prevent normal development of a child's brain.
Common pediatric brain tumors include tumors of primitive cells that have not matured into adult cell types (primitive neuroectodermal tumors or "PNETs"), tumors of the lining of the brain's fluid sacs (ependymomas), and benign tumors of the supporting cells of the brain (juvenile pilocytic astrocytomas).
To schedule an evaluation with a Burkhardt Brain Tumor Center specialist, please call 216.636.5860 or toll-free at 866.588.2264.