Disease Information

Brain Tumor: Astrocytoma / Glioma

Alternate Names: Anaplastic astrocytoma; glioblastoma multiforme; juvenile pilocytic astrocytoma (JPA); fibrillary astrocytoma; pleomorphic xantroastrocytoma (PXA); desembryoplastic neuroepithelial tumor (DNET)

Definition

Astrocytomas are tumors that arise from brain cells called astrocytes. Gliomas originate from glial cells, most often astrocytes. Sometimes the terms “astrocytoma” and “glioma” are used interchangeably. Here, we use “astrocytoma” to refer to these tumors as a group.

Astrocytomas are of two main types—high-grade and low-grade. High-grade tumors grow rapidly and can easily spread through the brain. Low-grade astrocytomas are usually localized and grow slowly over a long period of time. High-grade tumors are much more aggressive and require very intensive therapy. The majority of astrocytic tumors in children are low-grade, whereas the majority in adults are high-grade. These tumors can occur anywhere in the brain and spinal cord.

Common sites in children are the cerebellum (the area just above the back of the neck), cerebral hemispheres (the top part of the brain), and the thalamus or hypothalamus (located in the center of the brain).

Some of the more common low-grade astrocytomas are:

• Juvenile Pilocytic Astrocytoma (JPA)
• Fibrillary Astrocytoma
• Pleomorphic Xantroastrocytoma (PXA)
• Desembryoplastic Neuroepithelial Tumor (DNET)

The two most common high-grade astrocytomas are:

• Anaplastic Astrocytoma (AA)
• Glioblastoma Multiforme (GBM)
  

Incidence

Astrocytomas account for the majority of pediatric brain tumors. About 700 children are diagnosed with low-grade astrocytomas each year. In children, more than 80 percent of astrocytomas are low-grade; nearly 20 percent are high-grade.

Clinical Features and Symptoms

Clinical features and symptoms depend on the location of the tumor and the child’s age. The most common location is in the cerebellum. Patients with cerebellar tumors have symptoms that include headache, vomiting, and unsteadiness in walking. Tumors in the cerebral hemispheres commonly cause seizures; occasionally there is weakness of the arms and legs. Tumors in the hypothalamus often cause visual problems, while thalamic tumors cause headaches and arm or leg weakness.

Treatment Strategies

• Complete surgical removal of the tumor (resection) is the best option for tumors in areas where this can be done without damaging the normal, surrounding brain. For low-grade astrocytomas that are completely removed, no further therapy is needed. If the surgeon cannot completely remove the tumor and the child has not finished growing, chemotherapy may be given with later, delayed use of radiation therapy. This approach is taken because radiation causes more long-term side effects in younger children. Radiation therapy is used for older children and those whose tumors keep growing despite chemotherapy. About 90 percent of children with low-grade astrocytomas are alive five years from diagnosis.
  
• High-grade astrocytomas can rarely be removed totally because they often affect large areas of the brain by the time symptoms are obvious. All patients with high-grade astrocytomas receive both radiation therapy and chemotherapy regardless of age. Currently, the prognosis is poor in this group of patients. The subset of patients who have high-grade tumors that can be removed have survival rates of 35 percent to 40 percent after post-surgical irradiation with chemotherapy.

Current Research

• Research efforts for the low-grade astrocytomas focus on developing chemotherapy regimens that control tumor growth with fewer side effects on other organs of the body. Because these tumors grow slowly, the strategy is to give less intensive chemotherapy over long periods of time. For older children and those whose tumors progress despite chemotherapy, new radiation techniques are under study to “focally” deliver therapy with minimal effects on the normal brain.
  
• For high-grade tumors, our research focuses on the use of a new experimental drug call erlotinib, also known as Tarceva^TM or OSI-774. This drug belongs to a group of drugs called tyrosine kinase inhibitors, which are involved in controlling cell growth, migration, and death. This is the first time that this drug will be tested along with radiation treatment in children with brain tumors.  

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