Written by: Yazan Khan
Edited by: Srusti Shenoy
Glioblastoma is the most common brain cancer and is almost always lethal. The prognosis is poor with a life expectancy of half a year without treatment. Its incidence is greatest at the age of 60+ but patients exist in all age groups and disease occurs more typically in men than women. There are distinct grades of Glioblastoma. Grade II is marked by abnormal cellular shape. Grade III is marked by an increase in cell division. Grade IV is marked by rupture in brain vasculature. Genetic testing and histological analysis can accurately determine the grade.
Causes for cancer are mainly a result of genetic inheritance of susceptibility. Cancers are normal cells that accumulate enough mutation to begin rapidly dividing. These mutations are inherited from parents, increasing the likelihood of developing cancer as a result of more mutations throughout one's lifetime. Environmental factors like exposure to ionizing radiation can directly damage DNA and cause mutations.
Genetic mutations increase cell proliferation and resistance to death, allowing for cancer cells to rapidly grow. The AKT gene is a marker associated with this form of cancer. The gene is mutated and overexpressed, causing dysregulation in normal cell growth. This dysregulation causes a shift towards rapid anaerobic metabolism and inhibits the aerobic processes that occur in normal cells. This increases the demand for glucose in tumor cells and reduces the glucose available for the brain to function normally. Glioblastoma originates in astrocyte cells that are responsible for regulating blood flow in the brain. Disrupting this flow results in the following symptoms: seizures, cognitive impairment, vomiting, and blurry vision. An identifying feature of Glioblastoma is cranial hypertension and edema (swelling) as a result of fluid localization at the tumor. This causes internal bleeding, inhibits repair, cuts nutrient delivery to areas within the brain.
Diagnosis involves the use of MRI scans that image the soft tissues of the brain tissue and detect areas of swelling and the size of the mass. Scans will show a region of contrast indicative of tumor growth. Functional MRI (fMRI) can specifically assess the blood flow within the brain towards the site of the tumor. fMRI is particularly helpful to visualize where the tumor is located regarding critical areas. Activity during speech or motor function can be assessed and compared to the location of the tumor. An invasive biopsy is the most accurate and informative way to diagnose and understand the composition of a brain tumor. Surgeons will physically extract a sample from the tumor and send it for laboratory testing. The cerebrum is where tumors are most identified but imaging has shown the identification of some Glioblastomas in the brainstem.
The first defense against brain cancer is physically removing the tumor mass. This is not completely effective since cancer can invade critical areas, making complete physical removal impossible. Additional treatments like chemotherapy and radiation can eliminate remaining cancer cells. Chemotherapy medications are physically placed in the brain during surgery and are orally administered after surgery. Drugs like temozolomide damages DNA and causes cancer cell death. Radiation therapy uses high energy X-rays that are beamed towards the site of a tumor, killing cancerous cells. These methods also damage healthy cells and will result in harmful side effects like hair loss and weakness. There is diversity in tumor masses across people, personalized medicine is an emerging field that increases the effectiveness of cancer treatment. Genetic tests on cancer profile the tumor and its properties, medicine can be designed to act best for specific patients. Since treatment takes a toll on the patient's body, palliative treatment is concurrently administered to alleviate pain and improve quality of life.
REFERENCES
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Peruzzi, P. P., & Prabhu, V. C. (n.d.). Glioblastoma multiforme. AANS. Retrieved from https://www.aans.org/en/Patients/Neurosurgical-Conditions-and-Treatments/Glioblastoma-Multiforme
Precision or personalized medicine: Precision Medicine for Cancer. American Cancer Society. (2020, April 24). Retrieved from https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/precision-
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Qin, X., Liu, R., Akter, F., Qin, L., Xie, Q., Li, Y., Qiao, H., Zhao, W., Jian, Z., Liu, R., & Wu, S. (2021). Peri-tumoral brain edema associated with glioblastoma correlates with tumor recurrence. Journal of Cancer, 12(7), 2073–2082. https://doi.org/10.7150/jca.53198
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