half of all primary brain tumours and one-fifth of all primary spinal cord
tumours are gliomas, meaning they grow from glial
cells. In the brain, gliomas usually occur in the cerebral hemispheres
but may also develop in other areas, including the optic nerve,
the brain stem and the cerebellum. (Please refer to the diagram
below). Gliomas are classified into several groups because there
are different kinds of glial cells.
are the different glioma classifications:
A. WELL-DIFFERENTIATED (OR LOW-GRADE) ASTROCYTOMAS
Well-differentiated astrocytomas, also known as low-grade astrocytomas
or grade I or II astrocytomas, are tumours that contain cells that
are relatively normal and less malignant than the other two grades.
They grow slowly and may sometimes be completely removed through
surgery. However, even well-differentiated astrocytomas can be life-threatening
if they are present in areas of the brain that are not easily accessible.
In some cases, well-differentiated astrocytomas can also progress
or recur into higher-grade tumours.
B. ANAPLASTIC (OR HIGH-GRADE) ASTROCYTOMAS
Anaplastic astrocytomas, also called high-grade or grade III astrocytomas,
grow more rapidly than lower-grade astrocytomas and contain cells
with malignant traits. Surgery
followed by radiation therapy,
and often chemotherapy,
is used to treat anaplastic astrocytomas. There are many clinical
trials looking into new treatments for anaplastic astrocytomas.
GLIOBLASTOMA MULTIFORME (GBM)
GBM tumours, also called high-grade or grade IV astrocytomas, grow
rapidly, invade nearby tissue and contain cells that are very malignant.
GBM is among the most common and devastating type of primary brain
tumour that affects adults, and in some cases children. Doctors
usually treat glioblastomas with surgery followed by radiation therapy
and often chemotherapy, or a combination of these therapies.