Glioblastoma multiforme is the most aggressive form of glial cancer, a brain tumor made up of a variety of glial cells which are supportive cells in the nervous system. These glioblastomas grow rapidly and are difficult to treat. Prognosis tends to be poor, and even when successfully treated, glioblastoma multiforme tends to recur, growing back again in the same or a different brain location. While in many cases the cause remains unknown, doctors have pinpointed a few causes and risk factors for some instances of glioblastoma multiforme.
Genetic Factors
According to the International Radiosurgery Association, 80 percent of people who develop glioblastoma multiformae have multiple copies of chromosome 7 in the cells that turn cancerous. Other chromosomes that may affect the development of these types of tumors include chromosomes 6, 9, 10, Y, 13 ,14 and 19. A 1999 study published in the journal "Clinical Cancer Research" found that some chromosomal abnormalities that cause glioblastomas were more likely to be associated with whether or not the developing tumor responded to radiation treatment. For example, glioblastomas that develop in individuals with excess copies of chromosomes 7 and 19 tend to be resistant to radiation therapy.
Radiation Damage
Some instances of glioblastoma multiformae may occur in response to damage caused by high-dose ionizing radiation, such as the radiation used to treat other forms of brain cancer. Since ionizing radiation is the most effective treatment for glioblastoma multiforme, the possibility exists that treatment for one tumor may actually cause later recurrences.
Chemical Exposure
Many different chemicals have been implicated as possible sources of brain tumors, including glioblastoma multiforme. Chemicals that may affect the development of glioblastomas include petrochemicals, pesticides and formaldehyde.
Viruses
In some animals, oncogene viruses transport cancer-causing genes into cell DNA, effectively causing tumors to develop. Likewise, in humans, the viruses cytomegalovirus, JC virus and SV40 may induce the formation of glioblastomas in the brain. These viruses are DNA viruses which integrate into the host DNA. Evidence for the involvement of these viruses in glioblastoma multiforme development is conflicted, with some studies showing a connection and others failing to find a link, explains the "New England Journal of Medicine." Some scientists believe that these viruses are not a cause but instead are reactivated as a result of the cancer. The detection of viral particles in glioblastoma tumors may therefore be due to this kind of reactivation, not because the virus causes the tumor.
References
- International Radiosurgery Association: Glioblastomas
- "Clinical Cancer Research"; Chromosomal abnormalities in glioblastoma multiforme by comparative genomic hybridization: correlation with radiation treatment outcome; Huhn SL, et al.; June 1999
- "New England Journal of Medicine": Malignant Gliomas
- University of Maryland Medical Center: Brain Tumors
- Massachusets General Hospital: Brain Tumor Center
