Brain Cancer in Children

Brain cancer is one of the most deadly childhood cancers in the United States. Approximately 3.9 out of every 100,000 children are diagnosed with brain tumors every year.

Causes of Brain Tumors

As no single cause of brain tumors accounts for every case of brain cancer, the exact cause is unknown. However, medical professionals have suggested the following as possible triggers:

• birth defects
• environmental factors
• genetics.

Genetics and heredity have come under close scrutiny as possible brain cancer causes. However, only five to 10 percent of brain cancer tumors are inherited conditions, so genetics by no means fully explain brain cancer.

Brain Tumor Symptoms

Brain tumor symptoms vary depending on the size, location and spread of brain cancer. Severe brain tumor symptoms, such as seizures, are difficult to miss, but many brain cancer symptoms are more subtle and may be present for some time before a brain tumor diagnosis.

Possible brain tumor symptoms include:

• headaches
• irritability
• sleepiness.

However, as these are common conditions, they can easily be dismissed by parents or caregivers as a mild illness.

In addition to the brain tumor symptoms mentioned above, children with brain cancer may experience symptoms such as:

• changes in eating habits
• clumsiness
• vomiting.

Depending on the brain tumor's location, behavioral problems or personality changes may develop suddenly.

Types of Brain Cancer: Primary and Secondary Tumors

Brain cancers can be divided into primary and secondary tumors. A primary brain tumor originates within the brain. Primary brain tumors are usually confined to the brain, although they can spread to other locations.

Secondary brain cancer metastasizes, or spreads, to the brain from other organs. Metastatic cancers are more difficult to treat than primary tumors, as the cancer has spread over a larger area. While brain surgery can cure some types of primary brain tumors, brain surgery alone will not cure secondary brain cancer.

Benign and Malignant Brain Tumors

Primary brain tumors may be benign or malignant. A benign brain tumor is an unusual growth of otherwise healthy cells. Unless its location makes brain surgery impossible, surgical removal of the tumor is often the only treatment necessary.

A malignant brain tumor contains abnormal, cancerous cells that may spread into surrounding brain tissue. Brain surgery may cure some malignant brain tumors, but in many cases brain surgery alone can't remove all cancer cells, or the tumor's location makes surgery impossible. In such cases, radiation therapy or chemotherapy are employed, either in combination with brain surgery or as separate treatments.

Diagnosing Brain Cancer

A diagnosis of brain cancer begins with a physical examination, during which possible brain tumor symptoms are recorded. If symptoms suggest a brain tumor, the child may be sent for a neurological evaluation.

Neurological evaluations for possible brain cancer include vision tests, pupil reactions and eye reflexes. The optic nerve may be examined for signs of a brain tumor. Additionally, neurological evaluations typically test the following:

• abstract thinking
• balance
• coordination
• facial muscle control
• gag reflex
• head movement
• hearing
• memory
• mental alertness
• reflexes
• sensation
• smell
• strength
• tongue movement.

Brain Tumor Scans and Lab Work

If brain tumor symptoms and neurology results warrant further testing, diagnostic imagery tests such as CT scans and magnetic resonance imagery (MRI) may be ordered. A spinal tap to gather cerebrospinal fluid may reveal the presence of blood, protein or specific brain tumor markers in the cerebrospinal fluid. Some patients may require an endocrine evaluation, where the blood and urine are examined for unusual hormone levels.

Finally, if all test results suggest brain cancer, a brain tumor biopsy provides a definitive diagnosis. A brain tumor biopsy may require brain surgery to gather tissue samples. The brain surgeon may remove the entire tumor and send the tissue for microscopic analysis. In other cases, the surgeon may perform a biopsy with a needle, leaving the rest of the tumor intact.

If brain surgery isn't an option due to tumor location, fine needle aspiration may be a reliable alternative. A long, thin needle is inserted into the tumor through a hole drilled into the skull. Guided by a CT scan or MRI, the surgeon uses a needle to gather biopsy samples.

Classification of Brain Cancer

Biopsy results are examined microscopically to determine the type of brain cells comprising the tumor. Depending on the shape of the abnormal cells and the type of brain cell affected, brain tumors may fall into a number of different classifications, including:

• Astrocytoma: Half of all pediatric brain tumor symptoms are termed astrocytoma, a malignancy that starts in the astrocytoma cells, a type of support cell in the brain known as a "glial" cell. Astrocytomas are subdivided into infiltrating and non-infiltrating astrocytoma. Infiltrating astrocytoma spread throughout brain tissue and can't be cured by brain surgery. Non-infiltrating astrocytoma have much a much better prognosis, as the tumors do not tend to spread.
• Choroid Plexus Tumors: Usually benign, a choroidplexus tumor starts in the choroid plexus, which produces cerebrospinal fluid. Brain surgery is often a viable treatment.
• Craniopharyngioma: Craniopharyngioma are cancerous tumors located beneath the brain. They grow close to the optic nerves, making brain surgery difficult, although it is still possible in some cases. Some craniopharyngioma tumors can be cured with a combination of surgery and chemotherapy.
• Ependymoma: Arising from the brain's ependymal cells, ependymoma tumors prevent cerebrospinal fluid from leaving the brain's ventricles, which can cause brain swelling, or hydrocephalus. Some can be cured with brain surgery, as the tumor doesn't tend to spread.
• Ganglioglioma: Ganglioglioma are brain tumors composed of mature glial and neuron cells. High cure rates can be achieved with either brain surgery alone or with a combination of surgery and radiation therapy.
• Germ Cell Tumors: Germ cell tumors develop into sperm cells or ova (eggs) during embryonic development. Germ cells can lodge in the developing brain by mistake. Germ cell brain tumors are much more common in children than adults.
• Glioma: Glioma are tumors of the optic center, which can be cured with brain surgery. Glioma are not usually life-threatening, but surgery or tumor damage can result in vision loss.
• Medulloblastoma: Medulloblastoma are brain tumors that originate in primitive stem cells. Quick-growing tumors, medulloblastoma are treatable with brain surgery, chemotherapy and radiation therapy.
• Oligodendroglioma: Oligodendroglioma develop in glial cells, in this case in the oligodendrocytes. These brain tumors can't always be cured by brain surgery alone.

Resources

American Brain Tumor Association (2005). A primer of brain tumors. Retrieved September 4, 2007, from the ABTA Web site: http://www.abta.org/.

American Cancer Society (2005). What are children's brain and spinal cord tumors? Retrieved September 4, 2007, from the ACS Web site: http://www.cancer.org/docroot/home/index.asp.

Medical College of Wisconsin (1999). Brain tumors of children. Retrieved September 4, 2007, from the MCW Web site: http://www.mcw.edu/display/router.asp?DocID=1.

U.S. National Library of Medicine (2004). Brain tumor: Children. Retrieved September 4, 2007, from the NLM MedlinePlus Medical Encyclopedia Web site: http://www.nlm.nih.gov/medlineplus/.