BRAIN TUMOR - adults
A primary brain tumor is a group (mass) of abnormal cells that start in the brain.
Primary brain tumors include any tumor that starts in the brain. Primary brain tumors can start from brain cells, the membranes around the brain (meninges), nerves, or glands.
Tumors can directly destroy brain cells. They can also damage cells by producing inflammation, placing pressure on other parts of the brain, and increasing pressure within the skull.
The cause of primary brain tumors is unknown.
There are many risk factors that could play a role:
• Radiation therapy used to treat brain cancers increases the risk of brain tumors up to 20 or 30 years later.
• Some inherited conditions increase the risk of brain tumors, including neurofibromatosis, Von Hippel-Lindau syndrome, Li-Fraumeni syndrome, and Turcot syndrome.
• Lymphomas that begin in the brain in people with a weakened immune system are sometimes linked to infection by the Epstein-Barr virus.
These have not proven to be risk factors:
• Exposure to radiation at work, or to power lines, cell phones, cordless phones, or wireless devices
• Head injuries
• Hormone therapy
SPECIFIC TUMOR TYPES
Brain tumors are classified depending on:
• Location of the tumor
• Type of tissue involved• Whether they are noncancerous (benign) or cancerous (malignant)
• Other factors
Sometimes, tumors that start out less aggressive can change their biologic behavior and become more aggressive.
Tumors can occur at any age, but many types are most common in a certain age group. In adults, gliomas and meningiomas are the most common.
Gliomas come from glial cells such as astrocytes, oligodendrocytes, and ependymal cells.
Gliomas are divided into three types:
• Astrocytic tumors include astrocytomas (can be noncancerous), anaplastic astrocytomas, and glioblastomas.
• Oligodendroglial tumors. Some primary brain tumors are made up of both astrocytic and oligodendrocytic tumors. These are called mixed gliomas.
• Glioblastomas are the most aggressive type of primary brain tumor.
Meningiomas and schwannomas are two other types of brain tumors. These tumors:
• Occur most often between ages 40 and 70.
• Are usually noncancerous, but can still cause serious complications and death from their size or location. Some are cancerous and aggressive.
Other primary brain tumors in adults are rare. These include:
• Pituitary tumors
• Primary (central nervous system – CNS) lymphoma
• Pineal gland tumors
• Primary germ cell tumors of the brain