Astrocytoma

An astroctytoma is a form of a brain tumor that comes from astrocytes (a type of brain cell). 
There are many kinds of astrocytomas. They are separated into two categories; Low-grade astrocytomas and High-grade astrocytomas.
Low-grade astrocytomas.
Low-grade astrocytomas usually grow slowly and stay in one place. Because of this, many of them can be treated just with surgery. Once the tumor is taken out, often no other treatment is needed. As long as they get treatment, after five years, 90% of people with these astrocytomas are still alive.
One example of a low-grade astrocytoma is "pilocytic astrocytoma."
High-grade astrocytomas.
High-grade astrocytomas grow much more quickly and tend to spread throughout the body. Because of this, they are harder to treat and have worse prognoses than low-grade astrocytomas.
One example of a high-grade astrocytoma is "anaplastic astrocytoma". This type of tumor has to be treated with a chemotherapy called Temozolomide.