Although it’s been said on TV a lot lately, I cringe when I hear the words “brain cancer” because we neurosurgeons never say that. I think it’s because cancer is used for malignant tumors that spread throughout the body to other organs and malignant brain tumors rarely spread to other areas outside the brain. We always say brain tumor. Brain tumors are benign about half the time and the malignant brain tumors can be slow growing or very aggressive, but don’t metastasize (meta = across or over + stasis = stand) to other parts of the body.

Nerve cells in the brain rarely form tumors. Cells in the brain that “glue” the nerve cells together, called glial cells are the ones that can grow out of control. The most common glial cell is star-shaped under a microscope and is called an astrocyte. Astrocytomas are the most common malignant brain tumor, but can be very slow growing Grade I to fast growing Grade IV, also called a glioblastoma. Other glial cells are oligodendroglia (few branches) and microglia (tiny cells) but their tumors are less common.

The brain is covered with tissue layers called the meninges. An infection there is well known as meningitis. Tumors commonly grow from then meninges, called meningiomas. We call them brain tumors, but they are not of the brain, only inside the head. Most are very slow growing Grade I but some are more aggressive Grade II (called atypical) and a few are malignant Grade III.

Another “brain tumor” is a growth on the nerve of hearing, the acoustic neuroma. It is benign and usually presents with hearing loss in one ear. It can grow large enough to compress the vital lower brain stem and usually must be treated.

For more information on treatment, click on Gamma Knife Radiosurgery on the Home Page.