Pediatric Brain Cancers:

Brain cancers account for about 15% of pediatric cancers and are the second most common type of cancer in children. Since the brain controls learning, memory, senses (hearing, visual, smell, taste, touch), emotions, muscles, organs, and blood vessels, the presentation of symptoms varies accordingly.

Treatment of pediatric brain cancers (and non-malignant brain tumors) is more complex than is the treatment of some of the other childhood cancers. Surgery to remove the tumor is not always possible, either because the tumor is inaccessible or because surgical removal of the tumor would damage critical parts of the developing brain. Inoperable areas of the brain include the brain stem, thalamus, motor area, and deep areas of gray matter. The prognosis of a brain tumor depends not only on the type, grade, and size of the tumor, but on its location in the brain. Another reason that malignant brain tumors can be difficult to treat is because the blood-brain barrier prevents chemotherapy from entering the brain and reaching the tumor when given systemically.

Types of Childhood Brain Tumors

Many different types of brain tumors occur in children, and the nomenclature can seem daunting. Many brain tumors are named for both the type of cell from which the tumor originated and the location of the tumor in the brain

Medulloblastomas arise from primitive neuroectodermal tissue, or PNET. PNET is a general term for a collection of many different brain tumors which arise from undeveloped brain cells. Medulloblastomas are usually located in the cerebellum and are fast growing and highly malignant. They frequently spread, invading other parts of the central nervous system via the spinal fluid. Medulloblastomas account for the largest percentage of pediatric brain cancers.

Ependymomas arise from the cells that line the internal surfaces of the brain, thus, they are gliomas. The tumors arise from ‘ependyma,’ cells that line the fluid spaces of the brain and spinal cord. Ependymomas located in the cerebral hemispheres occur primarily in children and adolescents. Although these tumors are capable of malignant behavior, they are almost always benign.

Pilocytic Astrocytomas arise from brain cells which form part of the supportive system of the brain, in particular, cells called “astrocytes” for their star shaped appearance. This tumor are usually slow growing and many are considered curable. Astrocytomas are often cystic, in which case they are particularly easy to remove completely.

Optical nerve gliomas are slow growing tumors which form along the optic nerves. They usually occur in children under the age of 10. The common cell type is pilocytic astrocytoma.

Brain stem glioma, located in the brain stem, can be either slow or fast growing. Depending on the type of supporting tissue from which they arise, they can be either astrocytomas, anaplastic astrocytomas, glioblastoma multiforme, or a mixed tumor. In general, brain stem tumors are more common in children than they are in adults. Surgery is usually not possible in these tumors, and radiation and chemotherapy must be used instead.

Oligodendrogliomas are a slow growing tumor which arises from cells which make the myelin that insulates nerve fibers. They are located in the hemispheres of the brain, especially the frontal and temporal lobes, and in children are more common in the thalamus.

Gangliogliomas are usually slow growing, and rarely malignant. These tumors can be located anywhere in the brain, but are most often found in the temporal lobe. They arise from ganglia (a ganglion is a group of nerve cells). They occur most frequently in children and young adults.

Craniopharyngioma are benign (non-cancerous), congenital tumors. They are usually cystic and found primarily in children and adolescents.

Pineal Region Tumors are located in the pineal gland at the posterior portion of the third ventricle. The most common tumor of the pineal region is the germinoma. Germinomas (germ cell tumors) represent over one-third of the tumors in this region. Germinomas of the pineal region are most common in teenagers. Additional tumors found in this area include other embryonal type tumors, teratomas, astrocytomas, pineocytomas, and pineoblastomas.

Symptoms of Brain Tumors
The symptoms depend on the location and size of the tumor. Since the brain controls learning, memory, senses, emotions, muscles, organs, and blood vessels, the presentation of symptoms varies accordingly. Since young children often do not complain of the symptoms, parents must rely on their own observations of their child to be aware of signs and symptoms. Sometimes it is the child’s school teacher who picks up on the signs and symptoms of a child’s brain tumor

Symptoms can include:

·         a seizure not related to high fever

·         staring, repetitive automatic movements

·         persistent vomiting without any known cause (projectile vomiting), nausea

·         progressive weakness or clumsiness; neck tilt, squint

·         walking, balance problems

·         precocious puberty; growth retardation

·         sleep apnea

·         vision problems

·         headache, especially that wakes the child up at night or is early in the morning

·         pain, especially back pain, which should be taken seriously in a child

·         changes in personality, irritability, listlessness

Treatment for Brain Tumors

Children with brain tumors should be seen at a multi-disciplinary pediatric medical center, staffed with the following team: a pediatric neurosurgeon, a pediatric neuro-oncologist, a pediatric hem-onc, a pediatric neuro-radiolgoist, and a pediatric neuropsychologist. According to the NCI PDQ, radiation therapy of pediatric brain tumors is technically very demanding and should be carried out in centers that have experience in that area in order to ensure optimal results.

Brain tumors are treated with surgery, radiation, and chemotherapy. The specific treatment and prognosis depends on the type, grade, and location of the tumor. Depending on the type of tumor and the promptness of diagnosis, the 5 year survival rate is 40-80%. Long-term management of brain cancer survivors is complex and requires a multi-disciplinary approach.

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