Adult Brain Tumor Treatment Information for Physicians

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STAGE INFORMATION

Brain tumors are classified on the basis of tumor cell type and histologic grade. For some tumors, location and metastatic spread within the cerebrospinal fluid are also used in classification.[1]

Cerebral Astrocytic Gliomas

Gliomas constitute the most common primary central nervous system (CNS) tumors. Of the gliomas, astrocytomas of variable malignancy are the most prevalent. Cerebral astrocytomas are subdivided into categories (grades) based on the degree of tumor anaplasia and the presence or absence of necrosis.

These astrocytomas are relatively slow-growing tumors such as juvenile pilocytic and subependymal astrocytomas, which occur most frequently in children but can occur in adults.

These tumors are more infiltrative than the juvenile pilocytic and subependymal astrocytomas but are still relatively slow-growing tumors.

These tumors are highly anaplastic with obvious vascular abnormalities. This grade III astrocytoma grows more rapidly than the more differentiated astrocytomas.

This grade IV astrocytoma is a poorly differentiated, rapidly growing tumor that occurs most often in adults.

Brain Stem Gliomas

Brain stem gliomas are usually diagnosed on clinical evidence because diagnosis by biopsy might be hazardous. Tumors that diffusely enlarge the brain stem carry a worse prognosis than those that are more focal. Higher grades of malignancy (see above) carry poorer prognoses as well.

Cerebellar Astrocytomas

Although the majority of these tumors are of lower grade and frequently are curable, they vary in grade of malignancy. The higher grade lesions carry a worse prognosis, but prognosis is generally better than for their cerebral counterparts.

Ependymal Tumors

Ependymal tumors are considered to arise from ependymal cells that line the ventricles and from ependymal rests. They vary in grade of malignancy.

These tumors include myxopapillary ependymoma and well-differentiated ependymoma, and are often curable.

These tumors have more features of anaplasia and appear mitotically more active than the myxopapillary or well-differentiated ependymomas. Although previously considered to do worse than the well-differentiated ependymoma, conflicting evidence suggests that patients treated with surgery and radiation therapy might do nearly as well.

These are generally tumors of childhood and are considered by some to be primitive neuroectodermal tumors. They are rare.

Oligodendroglial Tumors

Oligodendroglial tumors are gliomas that arise from the oligodendroglia. They vary in grade of malignancy, and prognosis is related to grade.

These tumors are usually slow-growing and well circumscribed.

These tumors are comparable to the highly anaplastic gliomas in prognosis.

Mixed Gliomas

Mixed gliomas can occur with combinations of generally 2, but sometimes 3, different cell types: astrocytoma, ependymoma, and/or oligodendroglioma. Survival statistics are inexact for this group because the cell types and grade of the most malignant-appearing cells influence prognosis. In general, these tumors carry a prognosis that is between the prognoses of well-differentiated and anaplastic astrocytomas.

Medulloblastoma

Medulloblastoma is a rapidly growing tumor arising in the posterior fossa and is found almost exclusively in children and young adults. It has the tendency to spread from the brain to the spinal axis. Prognosis is dependent on the staging following surgical resection.

Pineal Region Tumors

Pineal parenchymal tumors vary in histology and grade of malignancy relative to patient age at occurrence. They can vary from the slow-growing pineocytoma to the more malignant and faster growing pineoblastoma. Astrocytomas can also grow in this location (see above), as can a variety of primary germ cell tumors: germinoma, embryonal carcinoma, choriocarcinoma, and teratoma. These uncommon tumors vary in prognosis. The absence of biopsy specimens in many series make the prognosis for each tumor type difficult to evaluate.

Craniopharyngiomas

Craniopharyngioma is a tumor that arises from the remains of a structure found in the developing embryo in the region of the pituitary gland. This tumor causes symptoms and signs by pressing on vital areas of the brain and the optic nerves; it also causes internal hydrocephalus by obstructing the foramen of Monro in children.

Meningiomas

Meningiomas arise from the meninges surrounding the brain and spinal cord and are generally slow-growing. There are other variants that constitute a group called malignant meningioma and include malignant meningioma, hemangiopericytoma, papillary meningioma, and meningeal sarcoma. Malignant meningiomas are more likely than other meningiomas to metastasize within the craniospinal axis.

Meningioma is usually curable with surgery if the initial resection is complete. The shape of the tumor is a prognostic factor and should be considered in planning surgery. Lobulated and mushrooming patterns of tumor growth lead to recurrences.[2]

The prognosis for patients with malignant meningioma is worse than for patients with the more well-differentiated meningiomas.

Choroid Plexus Tumors

Choroid plexus tumors are rare tumors arising from choroid plexus epithelial cells. The more benign form is choroid plexus papilloma; the more malignant form is called anaplastic choroid plexus papilloma. These latter tumors are most likely to spread within the craniospinal axis.

Primary CNS lymphoma is discussed in the PDQ primary CNS lymphoma summary.

References:

1. Levin VA, Leibel SA, Gutin PH: Neoplasms of the central nervous system. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds.: Cancer: Principles and Practice of Oncology. Philadelphia, Pa: Lippincott-Raven Publishers, 5th ed., 1997, pp 2022-2082.
2. Nakasu S, Nakasu Y, Nakajima M, et al.: Preoperative identification of meningiomas that are highly likely to recur. Journal of Neurosurgery 90(3): 455-462, 1999.

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