Definition and Description of Brain Tumors

Definition

Brain cancer occurs when malignant cells develop in the brain. This type of cancer is often referred to as a tumor. However, some brain tumors are not malignant or cancerous. A benign brain tumor is composed of non-cancerous cells and does not metastasize beyond the part of the brain where it originates. A brain tumor is considered malignant if it contains cancer cells, or if it is composed of harmless cells located in an area where it suppresses one or more vital functions.

Description

Brain cancer is the abnormal growth of cells in the brain. Though growths on the brain are often referred to as tumors, not all tumors are cancerous. Only malignant, or spreading cells, are called brain cancer. When a tumor does not spread it is a benign tumor. Brain cancer is the leading cancer in patients under the age of 35. There is no specific cause for brain cancer.

There are two categories of brain tumors: primary and secondary. Primary tumors start in brain tissue, while secondary tumors have spread to the brain from another area of the body. Primary tumors can be benign or malignant, and are classified by the tissue in which they begin:

• Glioblastoma multiforme is a higher-grade tumor that can arise from lower-grade gliomas.
• Gliomas, the most common primary tumors, start in the brain's glial (supportive) tissue. Gliomas include astrocytomas, glioblastomas, oligodendroglial tumors and ependymal tumors.
• Medulloblastomas come from early embryonic cells and more commonly occur in children.
• Meningiomas are related to the type of cells in the lining of membranes surrounding the brain and spinal cord. They are more commonly benign, but can be recurrent or malignant.
• Lymphoma arises from lymphocyte cells, usually in other parts of the body, but also can occur in just the brain or spinal cord.