Gliomas are a large group of brain and spinal cord tumors that originate from glial cells, a major brain cell that can develop into cancer. Symptoms, prognosis and treatment of malignant gliomas are determined by the patient’s age, tumor type and location of the tumor in the brain. These tumors tend to grow or invade into normal brain tissue, complicating treatment and making surgical removal difficult or even impossible. The risk of brain tumors increases with age, reaching a maximum risk around the ages of 75-84. Hypofractionated gliomas usually occur in children, while brain tumors are slightly more prevalent in men. The only risk factor for malignant glioma is prior radiation exposure to the brain, and family history factors account for less than 5% of the risk for this type of tumor, with some genetic disorders exacerbating the risk in pediatric patients but less in humans. There is no definite relationship between the development of malignant glioma and alcohol consumption, smoking and cell phone use.
There are different types of gliomas. Forty-two percent of brain tumors are benign, and 77% of malignant brain tumors are gliomas. Gliomas are named based on a specific type of glial cell in brain cells. According to the American Oncological Society, there are three types of gliomas, including astrocytoma, oligodendroglioma, and ventricular meningioblastoma.
Astrocytomas —- account for 35% of brain tumors and originate from astrocytes. The majority of these tumors cannot be cured because they spread through normal brain tissue. Astrocytomas are classified as low-grade malignant, moderately malignant, and highly malignant tumors based on pathology in microscopic histological sections. Glioblastoma, one of the most common malignant brain tumors in adults, grows very rapidly.
Oligodendroglioblastoma —- accounts for 4% of all brain tumors, it spreads in a similar manner to astrocytoma and is usually not curable by surgery.
Ventricular meningioma —- accounts for 2% of all brain tumors. This tumor is derived from ventricular meningeal cells, and because it does not spread to normal brain tissue, some ventricular meningiomas can be cured surgically.
What are the symptoms of glioma?
The symptoms of glioma are similar to those of other malignant tumors of the brain, depending on the location of the brain tissue it attacks. One of the most common symptoms is headache – about half of the patients with brain tumors have clinical manifestations of headache. Other common symptoms include seizures, memory loss, physical weakness, difficulty controlling limbs, visual symptoms, speech problems, cognitive decline, and personality changes. Different parts of the brain are affected and produce different symptoms.
As the tumor continues to grow and brain cells continue to be destroyed, some brain tissues are compressed and these symptoms may change or become more severe, causing edema in the brain and pressure on the skull.
How to diagnose glioma?
If your doctor suspects a brain tumor, or if you have persistent headaches and severe symptoms (such as seizures), you will need a cranial scan. A cranial scan includes CT or MRI. If the scan of the skull suggests a cranial tumor, a pathological biopsy will be used to diagnose a malignant glioma. The pathological biopsy can be performed alone or during surgical removal of the brain tumor.
3. How is glioma graded?
Gliomas are classified into various subtypes according to their different characteristics. Grade I tumors are slow-growing and can usually be surgically removed, while grade IV tumors are fast-growing, aggressive and difficult to treat.
According to the World Health Organization (WHO) literature in 2000, the widely used grading of malignant gliomas is as follows.
Grade I glioma, also known as astrocytoma multiforme is commonly seen in children.
Grade II gliomas are low-grade fibrous astrocytic gliomas.
Grade III gliomas are called undifferentiated astrocytic gliomas and they are usually considered to be highly malignant.
Grade IV refers to malignant gliomas, which means glioblastoma multiforme (GBM). At least 80% of malignant gliomas are glioblastoma multiforme and are considered highly malignant.
Oligodendroglial cell tumors are graded as follows.
Grade 2 or low-grade malignant oligodendroglioma
Grade 3 or highly malignant oligodendroglial cell tumor
Ventricular meningeal tumors are graded as follows
Ventricular meningioma
Interstitial ventricular meningioma (more aggressive).
Low malignant tumors are usually slow growing, but may change to highly malignant tumors over time.
How to treat glioma?
Depending on the location of tumor growth, histological classification, and malignancy classification, different treatment methods are available for malignant glioma. The patient’s age and physical condition also influence the treatment plan. The various treatments for glioma can be summarized as follows.
1. Surgical removal of the tumor is the primary treatment if the patient’s other organs are functioning relatively well and if the speech and behavioral functions of the brain are intact. Imaging techniques such as PET scans and functional MRI scans can help to preserve the function of the resected tumor intraoperatively. The goal of surgical treatment is to remove as much of the tumor as possible. Recurrence of tumor is very common.
2. Radiation therapy refers to the use of high-energy X-rays or other radiation to kill tumor cells.
Chemotherapy refers to the use of drugs to stop the growth of tumor cells, which can be injected or taken orally.
4. Supportive therapy is used to improve clinical symptoms or improve neurological function. Corticosteroids are used to relieve headaches or neurological symptoms by reducing tumor-induced brain edema, and antiepileptic drugs are used to control or prevent epilepsy.
The treatment of different gliomas is described as follows.
1. Treatment of low-grade malignant astrocytomas: According to the American Cancer Society, surgery is preferred for low-grade malignant astrocytomas (if feasible) because these tumors grow deep in the brain and become entangled with normal brain tissue, making surgery sometimes difficult. If surgery is not possible or the tumor cannot be completely removed, it should be followed by the use of radiation therapy, and these tumors are resistant to chemotherapy.
2. Treatment of highly malignant astrocytomas: Highly malignant astrocytomas (grade III mesenchymal astrocytomas or grade IV glioblastomas) are treated with radiotherapy.
Glioblastoma multiforme of grade III or IV) can still be considered for surgical treatment if feasible, although surgical treatment is no longer curative at this time. After surgery, the next step is radiation therapy, combined with chemotherapy. Sometimes surgery is not possible to remove the malignant tumor, and the doctor will simply use radiation therapy plus chemotherapy. If the tumor regresses or shrinks, surgery plus other chemotherapy regimens may be reconsidered.
3. Treatment of oligodendroglioma: For oligodendroglioma, surgery is the treatment of choice. Although not curable, surgery will help relieve symptoms and increase survival. Chemotherapy and/or radiation therapy may follow surgery, and again, chemotherapy or radiation therapy may help reduce the size of the tumor before surgery. If surgery is not possible, treatment with chemotherapy or a combination of radiation therapy is usually used.
4. Treatment of ventricular meningioma and mesenchymal ventricular meningioma: Unlike other gliomas, ventricular meningioma and mesenchymal ventricular meningioma do not grow intertwined with normal brain tissue and can be surgically cured if the tumor can be completely removed. Sometimes the tumor cannot be completely removed by surgery, and chemotherapy or additional radiotherapy should be administered after surgery.
V. What is the prognosis of glioma?
The prognosis is usually poor, especially for elderly patients with brain tumors. According to the World Health Organization (WHO), the average survival time for patients with grade IV glioblastoma is about 12 months. In the rare cases of mesenchymal astrocytoma (grade IV glioma), survival can be extended to as long as 3 years with conventional treatment. However, with the advent of new targeted therapies, drugs, gene therapy, and some experimental medical treatments (aimed at boosting the patient’s own immune system), more patients with glioma will be able to receive effective treatment.