Cancers of the brain and nervous system are the second most common type of childhood cancer, after leukemia (cancer of the blood or bone marrow).
With these types of cancer, clusters of cancer cells, or tumors, develop within the skull — on the inside or outside of the brain — and affect the nervous system, the messaging system that sends signals from the brain to other parts of the body.
When discovered early, cancers of the brain and nervous system are usually treatable. There are many different types, and doctors categorized them according to where the tumors are located, the type of cells involved, and how quickly they grow.
Discussed in this article are some of the most common types of brain and nervous system cancers.
Brain Stem Glioma
The brain stem, located deep in the back of the brain, consists of the midbrain, pons, and medulla. These structures coordinate all of the brain's messages. They also control many of the body's automatic functions, like breathing, heart rate, blood pressure, swallowing, digestion, and blinking.
A tumor that develops in any area of the brain stem is called a brain stem glioma. Tumors that occur in the pons (pontine gliomas) are the most common but are often the most difficult to treat. Tumors that occur in the midbrain and medulla are less common but usually more easily treated.
Symptoms of a pontine glioma may come on suddenly and worsen very quickly. These may include:
- double vision
- turning in of one eyeball
- drooping of the eyelid or one side of the face
- trouble swallowing
- trouble speaking and walking
Midbrain tumors may cause similar eye symptoms, along with headaches and vomiting. This is due to increased pressure in the head caused by a blockage of cerebrospinal fluid, the fluid that surrounds and cushions the brain and spinal cord.
Tumors of the medulla are associated with swallowing problems and limb weakness.
Because the brain stem is an area of the brain that generally can't tolerate surgery, brain stem gliomas are usually treated with radiation (high-energy X-rays that kill cancer cells).
Ependymoma
Along with cushioning the brain and spinal cord, cerebrospinal fluid helps preserve nerve tissue by keeping it healthy and removing waste products. Ependymomas are tumors that originate in brain cells that produce and store this fluid, and they mostly develop in children under age 5.
Ependymomas are classified according to their location, and most do not spread (metastasize) to other areas of the body. Those located in the top part of the head are called supratentorial. This type of tumor is associated with symptoms such as nausea, vomiting, and headaches from increased pressure within the brain, as well as weakness and vision problems.
Tumors found in the back of the head are more common. These are called infratentorial, and are also associated with nausea, vomiting, and headache, as well as trouble with coordination.
Supratentorial ependymomas often can be cured by surgery alone, while infratentorial ependymomas usually require much more aggressive treatment with surgery and radiation.
Primitive Neuroectodermal Tumor (PNET)
PNETs are a group of tumors that can occur anywhere in the brain, but whose cells look very similar under a microscope. Types of PNETs include medulloblastoma, pineoblastoma, retinoblastoma, and neuroblastoma. All of these tumors are able to metastasize through the cerebrospinal fluid that surrounds the brain and the spinal cord.
PNET symptoms generally depend on their size and location, but common ones include:
- headaches, nausea, and vomiting (especially in the morning) caused by increased pressure in the head
- weakness in the arms and legs
- vision problems
- seizures
- trouble with balance and coordination
Even though PNETs require aggressive treatment, including surgery, chemotherapy, and radiation therapy, recent medical advances have made a cure possible for the majority of children who have them.
Optic Nerve Glioma
The optic nerve sends signals to the brain about what the eye sees. A tumor that occurs along this pathway is called an optic nerve glioma.
These tumors mostly affect kids under age 10, and those with the genetic condition neurofibromatosis (which causes tumors to grow on nerve tissue) have an increased risk.
The most typical symptom is progressive vision loss. With slow-growing tumors, this may be hard to spot at first — especially in younger children who can't describe what they're seeing. With fast-growing tumors (or less aggressive ones that have reached a large size), vision problems will eventually become apparent.
Kids also may start tilting their heads repeatedly or experiencing what appear to be developmental delays such as clumsiness during walking, speech difficulties, or behavior changes. A condition called nystagmus (when the eyeballs appear to "jitter" involuntarily) also might appear. Sometimes, if the tumor is pressing on the pituitary gland, growth problems can result.
Optic nerve gliomas are usually treated with a combination of surgery, chemotherapy, and radiation. Most kids do well and their vision usually returns to normal. However, there is always a risk of some permanent vision loss after treatment.
Astrocytomas
Astrocytomas originate from star-shaped brain cells known as astrocytes. They come in four major subtypes: juvenile pilocytic astrocytoma (grade 1), fibrillary astrocytoma (grade 2), anaplastic astrocytoma (grade 3), and glioblastoma multiforme (grade 4).
Low-grade astrocytomas in kids are highly curable because they grow slowly, don't spread, and are often more like cysts than tumors, thus making them fairly easy to remove unless found in areas where surgery would be difficult (like the optic nerve). After surgery, there's a chance that chemotherapy or radiation won't be needed.
High-grade astrocytomas are more difficult to treat, usually because they're located in an area of the brain where surgery is more difficult. In this case, treatment may require chemotherapy and/or radiation.
Side Effects of Cancer Treatment
Kids who undergo radiation or chemotherapy for a brain tumor will often experience side effects that include fatigue, nausea, vomiting, and hair loss. Fortunately, once treatment ends these side effects go away.
Long-term effects of treatment that included surgery, called "late effects," may include cognitive delay, seizures, growth abnormalities, hormone deficiencies, visual and auditory problems, and the possibility of developing a second cancer, including a second brain tumor.
Because these problems sometimes don't become apparent until years after treatment, careful observation and regular screenings are needed to catch them as early as possible.
Reviewed by: Donna Patton, MD
Date reviewed: September 2009
