Brain tumors are masses of cells that grow within the brain. Slow-growing cells may form a benign, or noncancerous, tumor. Abnormal cells that grow rapidly may form a cancerous tumor.
What is going on in the body?
The brain is tightly contained within the closed cavity of the skull. There
is very little extra room within the bony skull cavity. A growing brain tumor
can destroy brain cells directly. Or, it may put pressure on the nearby tissue and destroy cells. These effects can occur with either a benign or a cancerous tumor.
A brain tumor that starts within the brain is known as a primary brain tumor. Often, a brain tumor grows from cells that metastasize, or spread, from a cancer elsewhere in the body. Some of the cancers that often metastasize the brain are as follows:
melanoma, a skin cancer
What are the causes and risks of the condition?
The people most at risk for brain tumors include:
children, especially those who have cancer elsewhere in the body
elderly people, especially those at risk for cancer in other areas of the body
people who have been exposed to pesticides, industrial solvents, and other chemicals
people who have certain genetic alterations
people who have certain inherited diseases, including neurofibromatosis
people who have received X-ray exposure to the head
people who have weak immune systems, such as those who have immunodeficiency disorders
Many other risk factors have been reported to increase the risk of brain
tumors. Research findings have been either unconvincing or conflicting.
Additional factors that need further study include:
household appliances, such as microwaves
viruses and other biological agents