BRAIN TUMORS
What Is a Tumor?
A tumor is a mass of tissue that's formed by an accumulation of
abnormal cells. Normally, the cells in your body age, die, and are
replaced by new cells. With cancer and other tumors, something
disrupts this cycle. Tumor cells grow, even though the body does not
need them, and unlike normal old cells, they don' t die. As this process
goes on, the tumor continues to grow as more and more cells are
added to the mass.
Primary brain tumors emerge from the various cells that make up the
brain and central nervous system and are named for the kind of cell in
which they first form. The most common types of adult brain tumors
are gliomas and astrocytic tumors. These tumors form from astrocytes
and other types of glial cells, which are cells that help, keep nerves
healthy.
The second most common type of adult brain tumors are meningeal
tumors. These form in the meninges, the thin layer of tissue that
covers the brain and spinal cord.
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