What is an Anaplastic Astrocytoma?
An Anaplastic Astrocytoma is a high-grade, or malignant, glioma, a tumor of the glial (supportive) tissue of the brain. Anaplastic astrocytoma and glioblastoma multiforme, account for approximately 10 percent of pediatric central nervous system tumors.
These tumors arise primarily in the cerebral hemispheres (65 percent). Approximately 20 percent can occur in the area of the thalamus and hypothalamus or the diencephalon (responsible for identification of sensation, such as temperature, pain and touch, regulation of appetite/weight and body temperature, as well as connecting the brainstem to the cortex). Another 15 percent can occur in the region of the cerebellum and brain stem known as the posterior fossa.The median age at diagnosis is 9 to 10 years old, and these tumors occur with equal frequency in boys and girls.
What causes an Anaplastic Astrocytoma?
Most high-grade gliomas occur sporadically or without identifiable cause. They do however, occur with increased frequency in families with neurofibromatosis type I, Li-Fraumeni syndrome, hereditary nonpolyposis colon cancer and tuberous sclerosis. They have also been associated with exposure to vinyl chloride and to high doses of radiation therapy to the brain.
What are the symptoms of an Anaplastic Astrocytoma?
Anaplastic Astrocytomas of the cerebral hemispheres and the diencephalon, called supratentorial anaplastic astrocytomas, produce a variety of symptoms as a result of increased pressure within the head, as well as more localizing symptoms as a function of their specific location, rate of growth and associated inflammation.
The duration of symptoms is variable from a slow, insidious onset to more abrupt presentations.
The following are the most common symptoms of an anaplastic astrocytoma, however, each child may experience symptoms differently.
Common symptoms may include:headache and lethargy,symptoms of increased pressure within the brain. These symptoms include:headache (generally upon awakening in the morning) vomiting , seizures - can occur with supratentorial high-grade gliomas but do so less commonly than do low grade lesions compression of surrounding brain structures - depending on the location of the tumor, increased pressure can cause:weakness and other motor dysfunction neuroendocrine abnormalitieschanges in behavior or thought processes. The symptoms of a brain tumor may resemble other conditions or medical problems.
How are Anaplastic Astrocytomas classified?
Gliomas are heterogeneous tumors that are classified according to their most aggressive appearing elements. The World Health Organization classification scheme includes 4 grades of glioma. Anaplastic astrocytoma is a grade III tumor. It is characterized as being of astrocytic origin but having increased numbers of cells (hypercellularity), abnormal cells and nuclei (cytologic and nuclear atypia), increased proliferation of cells (mitoses) and increased growth of blood vessels (vascular endothelial proliferation).
Anaplastic Astrocytomas are aggressive tumors that infiltrate adjacent normal brain tissue and have a significant tendency to spread outside of the central nervous system.
How is an Anaplastic Astrocytoma diagnosed?
•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.
•A CT scan can assess the density of tumor tissue as compared to normal brain as well as establish whether the tumor exerts any the mass effect (the effect of an additional space occupying mass within the closed cavity of the skull on the normal brain). Anaplastic astrocytomas most often appear as irregularly shaped masses. When intravenous dyes are injected, these tumors avidly absorb dye and therefore are referred to as enhancing lesions.
•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. MRI provides greater anatomical detail than CT scan and can better distinguish between tumor, tumor-related swelling and normal tissue. In addition, MRI can distinguish between hemorrhage and tumor cyst.
•Magnetic Resonance Spectroscopy (MRS) a test done along with MRI that detects the presence of particular organic compounds produced by the body's metabolism. It can identify tissue as normal or tumor, and may be able to distinguish between glial tumors and tumors of neuronal origin.
•Biopsy - a tissue sample from the tumor will be obtained either through a needle or by direct excision during a surgical procedure performed by a surgeon to confirm the diagnosis
What are the treatments for an anaplastic astrocytoma?
Specific treatment for an anaplastic astrocytoma 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 expect the disease to progress
• your opinion or preference
The primary modes of therapy for newly diagnosed Anaplastic Astrocytoma include maximal surgical removal, when possible, followed by radiation therapy. To date, no chemotherapy regimen has been demonstrated to increase survival in pediatric high-grade gliomas.
As with all pediatric cancers, care should be delivered at specialized centers where multidisciplinary teams can provide not only expert diagnostics and experienced medical, surgical and radiation oncologists, but also psychosocial support, neuro-psychological testing and specialized school plans all delivered in a child- and family-sensitive and friendly environment.
Treatment may include (alone or in combination)
Surgery has multiple roles in the management of anaplastic astrocytomas, including treatment of increased intracranial pressure, biopsy and tumor removal. For operable tumors, the extent of surgical removal is clearly related to prognosis.
Most high-grade gliomas cannot be completely removed because of the infiltrating fingers of tumor which characterize their growth. However, multiple studies have demonstrated that maximal removal results in greater survival.
Tumors of the cerebral hemispheres are in general more easily removed than those of the midline, diencephalic structures.
Near complete resection of anaplastic astrocytoma in combination with radiation therapy has been reported to produce a five-year survival rate as high as 40 percent, whereas incompletely removed tumors were associated with a 20 percent five-year survival rate. The infiltrating nature of these tumors makes removal difficult.
Technological advances such as the intra-operative MRI, where surgeons can visualize the tumor as they operate with MRI scans, can enhance efforts at resection of difficult tumors and thereby improve survival.
Radiation therapy uses high-energy rays (radiation) from a specialized machine to damage or kill cancer cells and shrink tumors.
Chemotherapy is 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. 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 a pill to swallow, 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.
How are side effects managed?
Side effects in the treatment of anaplastic astrocytoma can arise from surgery, radiation and chemotherapy.
To ensure that your child is in the best hands, procedures should be performed in specialized centers where experienced neurosurgeons, working in the most technologically advanced settings, can provide the most extensive resections while preserving normal brain tissue.
Radiation therapy often produces inflammation, which can temporarily exacerbate symptoms and dysfunction. To control this, inflammation steroids are sometimes necessary.
Some of the chemotherapy agents are associated with fatigue, diarrhea, constipation and headache. These side effects can be effectively managed under most circumstances with standard medical approaches.
Many specialized brain tumor treatment centers have now added staff who are expert in complementary or alternative medicine. These treatments, including acupuncture/acupressure, therapeutic touch, massage, herbs and dietary recommendations, can also help to control pain and side effects of therapy.
What is the expected outcome after treatment for anaplastic astrocytoma?
The best reported survival rates for radically removed tumors treated with adjuvant radiation therapy approaches 40 percent at five years. This is a minority of patients, however, and in most cases, the tumor cannot be completely removed.
The five-year survival rates for children whose tumors are incompletely removed remains less than 20 percent.
More complete removal of hemispheric tumors may be associated with greater survival.
What about progressive or recurrent disease?
Clinical trials and experimental therapies are available for patients with relapsed high-grade gliomas at specialized centers. Current trials include novel medications as well as new methods for the delivery of more traditional agents.