Introduction:
Glioblastoma is a primary tumor originating in the brain. They are the most common primary tumors. They are usually seen in adults. They are very aggressive cancer and do not respond to treatments, and have a poor prognosis. Glioblastoma is divided into two variants based on isocitrate dehydrogenase (IDH) mutation. They are IDH-wildtype glioblastoma and IDH-mutant astrocytoma.
What Is IDH-Wildtype Glioblastoma?
Isocitrate dehydrogenase or IDH-wildtype glioblastomas are seen in adults between the age of 65 and 75 years, with more prevalence in males than in the female population. They are aggressive cancer that originates from the cells that support the nerve cell (astrocytes). IDH-wildtype glioblastomas have an increased rate of recurrence and poor prognosis. Glioblastoma can occur anywhere in the brain. It is seen commonly in the cerebral hemispheres, mainly in the temporal lobe.
What Is the Cause of IDH-Wildtype Glioblastoma?
The actual cause of IDH-wildtype glioblastoma is not clear. Exposure to ionizing radiation can result in glioblastoma. The only potentially modifiable risk factor associated with IDH-wildtype glioblastoma is ionizing radiation. Some of the causes of glioblastoma can be associated with some inherited syndromes like -
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Radiation-Induced Glioma - Radiation-induced glioma is a type of secondary cancer that occurs in people with a history of intracranial radiation therapy.
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Inherited Tumor Syndrome - People with inherited tumor syndrome have an increased risk of developing certain types of cancer than normal people. One such cancer is IDH-wildtype glioblastoma.
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Neurofibromatosis Type 1 - Neurofibromatosis is a rare genetic condition causing brown spots and cancers in the skin. It can also cause developmental changes to the nervous system.
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Li-Fraumeni Syndrome - This is a hereditary disorder that has an increased risk of developing cancer. It can affect all the family members. It cannot be prevented. But with consistent screening and treatment, survival rates can be improved.
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Turcot Syndrome - It is a rare tumor that has abnormal growth of tissue or polyps in the large intestine or the presence of a tumor in the brain. People who have turcot syndrome have an increased risk of developing colorectal cancer, glioblastoma, and medulloblastoma.
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Ollier Syndrome - Ollier syndrome causes non-cancerous growth in the cartilage. They can also be present in the skull.
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Maffucci Syndrome - They are non-cancerous growth present in the bones and skin. Other than bone and skin, they can also be present in the brain and spinal cord.
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Lynch Syndrome - Lynch syndrome is an inherited disorder that increases the risk of developing many types of cancers.
What Are the Symptoms of IDH-Wildtype Glioblastoma?
The signs and symptoms are based on the tumor site and the extent of the tumor. The clinical features or the signs and symptoms of IDH-wildtype glioblastoma include -
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The focal neurological deficit is caused by any defect in the nerve, spinal cord, or brain that can result in a problem in a particular location. For example, the right arm, tongue, the left side of the neck, etc. It can also involve problems with hearing, speaking, and vision. The severity and location of the problem can be used to identify the part of the brain or nervous system affected by glioblastoma.
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Increased intracranial pressure results in headaches, behavioral change, fatigue or weakness, sleepiness, blurred vision, vomiting, etc.
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Seizures (uncontrolled disturbance occurring in the brain causing changes in movements or behavior and sometimes affecting consciousness).
How Is IDH-Wildtype Glioblastoma Diagnosed?
IDH-wildtype glioblastoma is diagnosed by the following methods -
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Magnetic Resonance Imaging (MRI) Scan - MRI uses a large magnetic field, radiation, and computer technology to produce a three-dimensional image of the brain and spinal cord.
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Computed Tomography (CT) Scan - CT scan uses a high amount of X-ray radiation and computer technology to produce a cross-sectional image slice of the brain and spinal cord. This will help understand the extent of cancer.
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Positron Emission Tomography (PET) Scan - A PET scan uses a radioactive drug to visualize the abnormal metabolic activities inside the body.
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Biopsy - A sample of tissue is removed from the tumor and examined under a microscope to know the stage of the cancer cells.
What Are the Treatment Options of IDH-Wildtype Glioblastoma?
The treatment options for IDH-wildtype glioblastoma include -
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Surgical Resection - Depending upon the extent and location of the tumor, surgical procedures are done to remove the tumor as much as possible. It is performed in patients below the age of 70 to prevent age-related complications.
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Adjuvant Chemotherapy - First-line chemotherapy for the treatment of IDH-wildtype glioblastoma is by using 75 mg of Temozolomide daily during the radiation therapy. Adverse effects of Temozolomide include nausea and bone marrow suppression resulting in thrombocytopenia (reduced platelet count) and neutropenia (reduced white blood cells or neutrophils). In elderly patients above 70 years, chemotherapy and radiation therapy are the treatment of choice. Surgical resection is contraindicated in patients above the age of 70 years.
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Adjuvant Radiation Therapy - Higher dosages of radiation are delivered to kill the cancer cells and prevent the growth of the tumor. It is used as adjuvant therapy after surgery to prevent the growth of cancer cells. 60 Gray of radiation is delivered over six weeks in combination with chemotherapy.
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Immunotherapy - By using our immune system to fight against cancer cells.
What Is the Prognosis of IDH-Wildtype Glioblastoma?
IDH-wildtype glioblastoma has a poor prognosis even after treating the disease. The survival rate after diagnosing and treating IDH-wildtype glioblastoma is less than two years. If not treated, patients will only have a survival duration of four months. Certain factors will cause a negative prognosis in the IDH-wildtype glioblastoma. If there is an increased necrotic area or if the tumor is located deep inside the brain, like in the thalamus, incomplete removal of glioblastoma, increased age, etc., can cause a decrease in the prognosis of IDH-wildtype glioblastoma. In case of recurrence of the glioblastoma, surgical therapy to remove the tumor, radiation therapy, and chemotherapy using Lomustine or Bevacizumab or a combination of both are advised.
Conclusion:
After the treatment of IDH-wildtype glioblastoma, continuous follow-up is done to prevent the progression of the disease. The first follow-up is done 24 to 48 hours after the initial treatment of the disease to check for any residual cancerous tissue are left. Then after every 8 to 12 weeks, follow-up is advised.
