The brain tumors found most often in children - Childhood Brain Tumor Facts

Childhood Brain Tumor Facts

Brain and spine tumors are the second most common cancers in children after leukemia. 

Brain Has Crucial Roles

The brain controls many important facets of everyday life, including emotions, thought, speech, vision, hearing and movement. The brain sends messages throughout the body via the spinal cord and cranial nerves in the head. The network of the brain and spinal cord is called the central nervous system (CNS). Tumors can develop in the spinal cord and cranial nerves.

The hard, bony skull protects the brain, and the bones (vertebrae) of the spine protect the spinal cord. A liquid called cerebrospinal fluid (CSF) surrounds both the brain and the spinal cord.

The brain has four main parts:

Cerebrum: The outer and largest part of the brain. It has two halves called hemispheres and is responsible for:

• Emotions
• Reasoning
• Language
• Movement of muscles
• Senses of seeing, hearing, smelling, touch
• Perception of pain

Basal ganglia: Found deeper inside the brain, these play a part in muscle movement.

Cerebellum: At the back of the brain, this section helps control and coordinate movement, such as walking and swallowing.

Brain stem: Located at the base of the brain, the brain stem has nerve fibers that carry messages between the cerebrum and the rest of the body. A small but important area, the brain stem plays a part in breathing and heartbeat.

Childhood Brain Tumor Types

Because the brain and spinal cord are made up of many kinds of tissues and cells, many types of tumors – both benign and malignant– can develop in these areas. These tumors may require different treatment and have different outlooks.

Even when brain tumors are benign, they can cause serious problems. Although non-cancerous brain tumors usually grow slower than cancerous brain tumors, they may damage and press against normal brain tissue or the spine as they grow.

Childhood brain and spinal cord tumors differ from adult tumors. The location where they develop, the type of cell in which they develop, and their treatment and outlook often are different.

Brain tumors are classified by the types of cells they contain. This determines how they grow and what kind of treatment they require.

The brain tumors found most often in children are the following.

Medulloblastoma

Astrocytoma: These form in the cerebrum in cells called astrocytes. They usually grow slowly, but higher-grade tumors spread more quickly. Since they mix with normal brain tissue, they can be difficult to remove surgically. They may spread along pathways of CSF but seldom spread outside the brain or spinal cord. Glioblastoma is the highest grade astrocytoma and the fastest growing.

Diffuse intrinsic pontine glioma: This dangerous tumor often has a poor prognosis. It grows in a vital area of the brain called the pons, which is in the brain stem.

Ependymomas develop in the brain lining, usually in the posterior fossa or along the spinal cord in glial cells. About five percent of childhood brain tumors are ependymomas. They begin in cells that line the ventricles or central canal of the spine. Ependymomas do not usually spread outside the brain or spinal cord, but they may block CSF, causing hydrocephalus.

Primitive neuroectodermal tumors (PNET): These aggressive tumors can develop anywhere in the brain, but they are usually in the frontal, temporal or parietal lobes.

Pineoblastomas: A type of PNET that develops in pineal gland and can be difficult to treat.

Craniopharyngiomas: These slow-growing tumors start above the pituitary gland but below the brain. They may press on the pituitary gland and hypothalamus, causing hormone problems. Since they start near the optic nerves, they can cause vision problems and be difficult to remove without damaging vision.  

Mixed glial and neuronal tumors: Certain tumors that develop in children and young adults (and rarely in older adults) have both glial and neuronal cell components. They tend to have a fairly good prognosis.

• Pleomorphic xanthoastrocytoma (PXA) and dysembryoplastic neuroepithelial tumors (DNETs) look as if they could grow quickly when viewed under the microscope, but these tumors tend to be fairly benign, and most are cured by surgery alone.
• Ganglioglioma is a type of tumor that has both mature neurons and glial cells. Most can be cured by surgery alone or surgery combined with radiation therapy.

Choroid plexus tumors: These rare tumors start in the choroid plexus within the ventricles of the brain. Most are benign and can be removed by surgery.

Other tumors that start in or near the brain

Meningiomas: These tumors begin in the meninges, the tissue around the outer part of the brain and spine. They may press on the brain or spinal cord. Meningiomas are almost always benign and are usually cured by surgery. If they are near vital structures in the brain, they may need additional treatment.

Chordomas start in the bone at the base of the skull or at the lower end of the spine. They can injure the nervous system by pressing on it. They usually do not spread to other areas.

Germ cell tumors: Developing from germ cells, which normally form eggs in women and sperm in men, these are rare tumors. They form in the fetus when germ cells move to abnormal locations, including the brain. Germ cell tumors of the nervous system are usually found in children, most commonly in the pineal gland or above the pituitary gland.

Brain metastases: Cancers that metastasize (spread) to the brain from other areas of the body are called metastases. These are treated differently than primary brain cancers.