Glioblastoma multiforme (GBM) is one of
150 recorded brain tumors (Bellenir, 2007), accounting for 78% of 18,500 cases
of all malignant central nervous system cancers (Choudhury et al, 2005).
Unfortunately, it is the most invasive, malignant, highly vascularized,
infiltrative, and lethal glial tumor (Choudhury et al, 2010) with a poor
prognosis. (Bellenir, 2007) The World Health Organization categorizes
glioblastoma to be a high-grade (IV) fast growing astrocytoma containing dead
tumor cells, developing in the cerebrum, especially in the frontal and temporal
lobes. (Bellenir, 2007) The median age of diagnosis for glioblastoma is 50 to
70 and it is more prevalent in men than women.
Glioblastoma multiforme is characterized by
differentiated cells with multinuclei in the presence of nuclear atypia,
mitoses, microvascular proliferation, and pseduopalisading necrosis (Chodhurey
et al, 2005).
Glioblastoma multiforme has two
mechanisms of development. It may develop de novo (primary development), or it
can originate from low-grade astrocytomas (secondary development). Primary
tumors can be classified as glial or non-glial functioning as either benign or
malignant. (Bellenir, 2007) An adult diagnosed with a primary tumor will only live
for six months. The primary tumor over expresses the epidermal growth factor,
mutation in the phosphatase and tension homolog on the chromosome, and
deletions of the cyclin-dependent kinase inhibitor 2A. (Chodhurey et al, 2005)
Unlike primary tumors, secondary tumors
are more common in children. The secondary tumors will contain mutation in the tumor
protein 53 (TP53) and over expresses the platelet derived growth factor
(PDGFR).
Current therapies for glioblastoma
multiforme include surgery, radiation, and chemotherapy. Decisions as to what
treatments are used are based on the specific condition of the patient. (Bellenir
et al, 2007)
In surgery, the neurosurgeon’s challenge
is to remove as much of the brain tumor as possible. Common procedures include
craniotomy and sterotactic biopsy. However, even if 90% of the tumor is removed
a patient will only live for 9-15 months. Because glioblastoma is a high-grade
glioma, it forms tentacle like structures that invade surrounding tissue, making
surgery a less likely option. (Bellenir et al, 2007)
If surgery is not an option, radiation,
the use of high-energy x-ray to kill cancer cells, can be used. The main types
of radiation include standard external beam radiotherapy, proton beam
treatment, and sterotactic radiosurgery. (Bellenir et al, 2007)
The final treatment, chemotherapy only
positively effects 20 percent of all patients. Chemotherapy functions by
causing cell damage that is better repaired by normal tissue than tumor tissue.
Resistance occurs if the tumor tissue survives, and it is unable to respond to
the drug. Resistance may also occur, if the drug is unable to pass through the
blood brain barrier. (Bellenir et al, 2007)
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