Brain / CNS Tumors Support Group

A brain tumor is any intracranial tumor created by abnormal and uncontrolled cell division, normally either found in the brain itself (neurons, glial cells (astrocytes, oligodendrocytes, ependymal cells), lymphatic tissue, blood vessels), in the cranial nerves (myelin-producing Schwann cells), in the brain envelopes (meninges), skull, pituitary and pineal gland, or spread from cancers primarily located in other organs (metastatic tumors). Brain tumors may be benign or malignant.

Primary (true) brain tumors are commonly located in the posterior cranial fossa in children and in the anterior two-thirds of the cerebral hemispheres in adults, although they can affect any part of the brain.

In the United States in the year 2000, it was estimated that there were 16,500 new cases of brain tumors, which accounted for 1.4 percent of all cancers, 2.4 percent of all cancer deaths, and 20–25 percent of pediatric cancers. Ultimately, it is estimated that there are 13,000 deaths/year as a result of brain tumors.

Metastatic cancers are far more common than primary tumors of the brain and spinal cord.

Aside from exposure to vinyl chloride or ionizing radiation, there are no known environmental factors associated with brain tumors. Mutations and deletions of so-called tumor supressor genes are incriminated in some forms of brain tumors. Patients with various inherited diseases, such as Von Hippel-Lindau syndrome, multiple endocrine neoplasia, neurofibromatosis type 2 are at high risk of developing brain tumors.

In contrast to tumors originating elsewhere in the body, differentiating primary "brain tumors"—these are the true brain tumors, arising exclusively from cells normally present in the brain itself—into benign and malignant is of relative and limited clinical value, since even histologically-benign tumors grow by infiltration of healthy brain tissue and, in time, tend to transform into malignant forms (anaplastic degeneration). True benign intracranial tumors arise mainly from the meninges (meningiomas; about 95% are benign), pituitary gland (pituitary adenomas) and the myelin sheath of cranial nerves (neuromas or Schwanomas, e.g. acoustic neuroma).

Meningiomas, with the exception of some tumors located at the skull base, can be successfully removed surgically, but the chances are less than 50%. In more difficult cases, stereotactic radiotherapy remains a viable option.

Most pituitary adenomas can be removed surgically, often using a minimally invasive approach through the nasal cavity and skull base (trans-nasal, trans-sphenoidal approach). Large pituitary adenomas require a craniotomy (opening of the skull) for their removal. Radiotherapy, including stereotactic approaches, is reserved for the inoperable cases.

Although there is no generally accepted therapeutic management for primary brain tumors, a surgical attempt at tumor removal or at least cytoreduction (i.e., removal of as much tumor as possible, in order to reduce the number of tumor cells available for proliferation) is considered in most cases[5]. However, due to the infiltrative nature of these lesions, tumor recurrence, even following an apparently complete surgical removal, is not uncommon. Postoperative radiotherapy and chemotherapy are integral parts of the therapeutic standard for malignant tumors. Radiotherapy may also be administered in cases of "low-grade" gliomas, when a significant tumor burden reduction could not be achieved surgically.