Astrocytomas are part of a group of tumours called gliomas, which develop from the main supporting cells (glial cells) in the brain or spinal cord. Astrocytomas are the most common type of glioma, and develop from a star-shaped glial cell called an astrocyte. Although they can spread to other parts of the brain or spinal cord, they do not spread to other areas of the body. More likely to occur in older people, astrocytomas can be slow or fast growing. The fast growing type tends to occur mostly in adults.

These tumours are classified depending on how abnormal the cells appear and the growth patterns they exhibit:

  • Pilocytic Astrocytomas: form fluid-filled cavities (cysts) and may become very large.
  • Diffuse Astrocytomas: contain small cysts and mucous-like fluid.
  • Anaplastic Astrocytomas: have tentacle-like projections that grow into surrounding tissue, making them difficult to completely remove during surgery.
  • Astrocytoma Grade IV (glioblastoma): contain cystic material, calcium deposits, blood vessels, and/or a mixed grade of cells.

Radiation treatment has become substantially safer, and most patients do not suffer major problems as a consequence. However, it is still not recommended in children under 3 years of age, since it can damage their developing brain cells. Quite often, oncologists will follow a course of radiation with chemotherapy treatment to slow the progression of the tumour.