Primary brain tumor

Alternative names:

astrocytoma; brain tumor - primary; ependymoma; glioblastoma multiforme; glioma; medulloblastoma; meningioma; neuroglioma; oligodendroglioma

Definition:

A mass created by growth of abnormal cells or uncontrolled proliferation of cells in the brain.

Causes, incidence, and risk factors:

Primary brain tumor includes any tumor that originates in the brain. Tumors may be localized to a small area, invasive (spread to nearby areas), benign (noncancerous), or malignant (cancerous). Tumors can directly destroy brain cells. They also can cause indirect damage to cells from inflammation, compression from growth of the tumor, cerebral edema (brain swelling), and increased intracranial pressure (the pressure within the skull).

Classification of brain tumors depends on the exact site of the tumor, type of tissue involved, benign or malignant tendencies of the tumor, and other factors. Childhood nervous system tumors are classified as infratentorial (located below the tentorium cerebelli) meaning they are in the posterior third of the brain, or as supratentorial meaning they are within the anterior two-thirds of the brain. Central nervous system tumors account for about 20% of all childhood cancers. They are 2nd in incidence, only surpassed by leukemias. Two-thirds of brain tumors in children are infratentorial with peak ages of 5 to 9 years. The annual incidence in children less than 15 years old is 2.4 per 100,000. More than 1,200 new cases occur each year.

The cause of primary brain tumor is unknown. Some tumors (retinoblastoma, for example) tend to be hereditary. Others tumors (craniopharyngioma) are congenital. Tumors may occur at any age, but many have a particular age group in which they are more common. The most common childhood brain tumors are astrocytoma, medulloblastoma, ependymoma, and brain stem glioma. Gliomas account for 75% of brain tumors in pediatrics, but only 45% in adults. Outside of retinoblastomas, most brain tumors are rare in the first year of life.

Specific symptoms, treatment, and prognosis (probable outcome) vary according to the site and type of the tumor and the age and general health of the person.

SPECIFIC TUMOR TYPE INFORMATION
Cerebellar astrocytoma:

• accounts for 10 to 30% of pediatric brain tumors (peak age is 5 - 8 years old)
• usually benign, cystic, and slow-growing
• presenting signs usually include clumsiness of one hand, gait changes (stumbling to one side), headache, and vomiting
• there is a 38 to 94% cure rate based upon the tumor type
• single or combination therapy includes surgery, radiation therapy, and chemotherapy

Medulloblastoma:

• most common pediatric brain tumor (20 to 25% of posterior fossa tumors)
• occurs more frequently in boys than girls, and in infants more than older children and adults; peak age is 3 - 5 years old
• presenting signs include headache, vomiting, ataxia, and lethargy
• can spread (metastasize) along the spinal cord
• surgical removal alone is not curative; radiation therapy and/or chemotherapy are often used
• about 30 to 50% of children are disease-free in 10 years
• if relapse occurs it is usually within the first 5 years of therapy
• children under 4 often have poorer outcomes because of the high incidence of metastatic disease at diagnosis in this age group; as well as lower doses of radiation used to reduce late effects of therapy

Ependymoma:

• accounts for 8 to 10% of pediatric brain tumors (3rd most common)
• tumor growth rates vary
• tumors located in the ventricles of the brain and obstruct the flow of CSF
• presenting signs include headache, vomiting, and ataxia
• single or combination therapy includes surgery, radiation therapy, and chemotherapy
• overall childhood survival is less than 30%; low-grade tumors have a 5-year survival rate of 80%; high-grade tumors may be fatal

Brainstem glioma:

• tumors of the pons and medulla
• occur almost exclusively in children
• accounts for 10 to 15% of primary brain tumors in children; average age is 6 years old
• may grow to very large size before symptoms are present
• presenting signs include: double vision, facial weakness, difficulty walking, vomiting
• surgical removal is often difficult due to the location of the tumor
• radiation therapy and chemotherapy are used to shrink the tumor size and prolong life
• overall 5-year survival rate is 20 to 30%

Craniopharyngioma:

• tumor located near the pituitary stalk
• often benign, but close to vital structure making surgical removal difficult
• rare, less than 5% of childhood brain tumors; average age is 7 - 12 years old
• presenting signs include vision changes, headache, weight gain, endocrine changes
• treated with combination therapy, usually surgery and radiation therapy; there is some controversy over the optimal approach to therapy
• survival and cure rates are favorable, though endocrine dysfunction may persist as well as the effects of radiation on cognition (thinking ability)