 Low-grade Gliomas
|
|
 |
|
|
|
|
|
|
|
Low-grade gliomas comprise a class of slow growing, less aggressive tumors of the central nervous system. They most commonly arise from a specific type of glial cell known as an astrocyte. Astrocytes make up the supportive network of the brain. These cells are named for their star-like appearance.
Astrocytomas are the most common primary central nervous system tumor found in children, representing approximately 50 percent of pediatric brain and spinal cord tumors. There are four major types of astrocytomas, classified according to their appearance under a microscope:
|
|
|
- pilocytic astrocytoma or grade I astrocytoma
- fibrillary astrocytoma or grade II astrocytoma
- anaplastic astrocytoma or grade III astrocytoma (see high-grade gliomas)
- glioblastoma multiforme or grade IV astrocytoma (see high-grade gliomas)
|
|
Grade I or pilocytic astrocytomas and grade II or fibrillary astrocytomas belong to the class of tumors knows as low-grade gliomas.
Low-grade gliomas are also classified according to the location of the brain from which they originate. This includes:
|
|
|
- cerebellar pilocytic astrocytoma
- cervico-medullary astrocytoma
- optic pathway glioma
- tectal glioma
- thalamic/hypothalamic astrocytoma
|
|
Other types of low-grade gliomas include:
|
|
|
- oligodendroglioma
- ganglioglioma
- pleomorphic xanthoastrocytoma
|
|
|
|
Medical research has identified an association between the development of some types of low-grade gliomas and certain genetic syndromes. There is a strong association between neurofibromatosis and optic pathway gliomas. Children with the syndrome tuberous sclerosis also have an increased incidence of tumors of glial origin. The vast majority of children with low-grade gliomas however, develop these tumors spontaneously, meaning there is no identifiable cause.
|
|
|
|
|
|
The following are the most common symptoms of low-grade gliomas. However, each child may experience symptoms differently. Symptoms vary depending on size and location of tumor.
Due to the relatively slow growth rate of low-grade gliomas, children with these tumors tend to present to the doctor with subtle symptoms that have been occurring for many months. The presenting signs and symptoms are most often related to tumor location:
|
|
|
- low-grade gliomas of the visual pathway generally present with a change or loss of vision
- low-grade gliomas arising from the hormone center of the brain may present with weight gain or loss and/or premature puberty
|
|
The symptoms of a brain tumor may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.
|
|
|
|
|
|
In addition to a physical examination, diagnostic procedures for low-grade gliomas may include:
|
|
|
- computerized tomography scan (also called a CT or CAT scan) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. CT scans are more detailed than general x-rays. For low-grade gliomas, a CT scan of the brain is usually done.
- magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body. For low-grade gliomas, an MRI of the brain is usually done. In rare cases when low-grade gliomas spread to the spine, an MRI of the spine may also be ordered.
- biopsy - in many cases, a tissue sample from the tumor will be taken through a needle during a simple surgical procedure performed by a surgeon to confirm the diagnosis. Exceptions include low-grade gliomas of the optic pathway and brain stem. Due to the very delicate structures in these areas, surgery is generally avoided.
|
|
|
|
Specific treatment for low-grade gliomas will be determined by your child's physician based on:
|
|
|
- your child's age, overall health, and medical history
- type, location, and size of the tumor
- extent of the disease
- your child's tolerance for specific medications, procedures, or therapies
- how your child's doctors expects the disease to progress
- your opinion or preference
|
|
Treatment may include (alone or in combination):
|
|
|
- surgery - usually the first step in the treatment of brain tumors. The goal is to remove as much of the tumor as possible while maintaining neurological function.
- chemotherapy - a drug treatment that works by interfering with the cancer cell's ability to grow or reproduce.
Different groups of chemotherapy drugs work in different ways to fight cancer cells and shrink tumors. Chemotherapy may be used alone for some types of cancer or in conjunction with other therapy such as radiation or surgery. Often, a combination of chemotherapy drugs is used to fight a specific cancer. Certain chemotherapy drugs may be given in a specific order depending on the type of cancer it is being used to treat. While chemotherapy can be quite effective in treating certain cancers, the agents do not differentiate normal healthy cells from cancer cells. Because of this, there can be many adverse side effects during treatment. Being able to anticipate these side effects can help the care team, parents, and child prepare, and, in some cases, prevent these symptoms from occurring, if possible.
Chemotherapy is systemic treatment, meaning it is introduced to the bloodstream and travels throughout the body to kill cancer cells. Chemotherapy can be given:
- as an injection into the muscle or fat tissue
- intravenously (directly to the bloodstream; also called IV)
- intrathecally - chemotherapy given directly into the spinal column with a needle
- radiation therapy - using high-energy rays (radiation) from a specialized machine to damage or kill cancer cells and shrink tumors.
|
|
The treatment of the child with a low-grade glioma involves multidisciplinary care. Members of this team include neuro-surgeons, neuro-oncologists, radiation oncologists, neurologists, neuropsychologists, nurses, social workers, complementary medicine physicians and school liaison professionals.
|
|
|
|
|
|
The prognosis for a child with a low-grade glioma is determined by tumor grade, location and in some cases, age of the child at diagnosis. Many low-grade gliomas are treated initially with surgery alone and then monitored for evidence of regrowth. Grade I or pilocytic astrocytomas are sometimes cured with complete surgical removal alone. In instances where due to location, surgery is not an option (optic pathway or brain stem gliomas), is a limited option (thalamic/hypothalamic or cervico-medullary gliomas) or if after tumor removal, the tumor begins to grow again, chemotherapy is often recommended. Radiation therapy is generally reserved for children whose tumors have grown after chemotherapy. Due to the potential side effects of radiation, including effects on learning and hormone function, it is best avoided in young children (especially children less that age 3 years).
|
|
|
|
|
|
There are numerous standard and experimental treatment options for children with progressive or recurrent low-grade gliomas. Dana-Farber Cancer Institute is one of nine institutes in the nation belonging to the Pediatric Brain Tumor Consortium. The consortium is dedicated to the development of new and innovative treatments for children with newly diagnosed as well as progressive or recurrent brain tumors.
|
|
|
|
|
|
Children's Hospital and Dana-Farber Cancer Institute are conducting numerous research studies that will help clinicians better understand and treat low-grade gliomas. For more information on current research, see the Brain Tumor Program.
|
|
|
