High Grade Glioma in Children

The brain is made up of several types of cells, two of which are neurons and glia. There are also different types of glial cells, including oligodendrocytes and astrocytes. Gliomas are tumors of the glial cells, and more than two-thirds of childhood brain tumors are gliomas. In children under the age of 15, brain tumors comprise approximately 20 percent of diagnosed cancers. This article will define and explain what high-grade gliomas are in the childhood population.

Types

• The most common type of glioma are astrocytomas, which start in the astrocyte cells. The different kinds of astrocytomas are pilocytic astrocytoma (the most benign of the astrocytomas), fibrillary astrocytoma, anaplastic astrocytoma and glioblastoma multiforme (the most malignant of the brain tumors).

Diagnosis

• CT scans and MRIs are commonly used to locate and diagnose a brain tumor, but to ascertain what type it is, surgery needs to be done to obtain tissue. Other tests may be done to see if the cancer has spread anywhere else in the body. These tests include hearing tests, blood tests to measure kidney and liver function and hormone levels, and a lumbar puncture (spinal tap) to examine spinal fluid for any malignancies.

Grading

• Astrocytomas are ranked on a grading system developed by the World Health Organization, similar to the staging of other types of cancers. Grade I gliomas are the least dangerous, and Grade IV are the most aggressive. The term high-grade glioma refers to Grade III and Grade IV gliomas.

Treatment

• As with other brain tumors, surgery tends to be the first step in treatment with high-grade gliomas. The ideal surgery is a gross total resection, which means the tumor has been entirely removed, along with a margin of tissue around it, and when the surgery is done, no visible tumor remains. Radiation is commonly used after surgery. For high-grade gliomas, surgery and radiation provide control of the disease, as opposed to a cure, because of the aggressiveness of the cancer.

  Chemotherapy for high-grade gliomas is debatable. The use of it has been controversial, but it is still used because of the poor success rate of surgery and radiation. Because there is no standard of care for chemotherapy for children with high-grade gliomas, there is no documented benefit that would make it a standard part of treatment for these tumors. Chemotherapy and other targeted treatments are currently being explored in clinical trials.

Risk Factors

• Some genetic syndromes like Li-Fraumeni syndrome or von Hippel-Lindau disease are risk factors for developing a brain tumor, but only a small number of children diagnosed have these syndromes. If a child has had radiation to the head for a previous cancer, that is also a risk factor for developing a later brain tumor. Possible risk factors are being further examined, such as a mother's smoking or consuming alcohol during the pregnancy.