Approximately 42% of brain tumors are benign, and 77% of malignant brain tumors are gliomas. Gliomas are the most common large group of brain and spinal cord tumors that originate in glial cells and tend to grow or invade into normal brain tissue, making treatment complicated and surgical removal difficult or even impossible. 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 astrocytomas, oligodendrogliomas, and ventricular meningeal cell tumors.
Astrocytomas —- account for 35% of brain tumors and originate from astrocytes. Since it will spread through normal brain tissue, the majority of these tumors cannot be cured. Astrocytomas are classified as low-grade malignant, moderate-grade malignant and highly malignant tumors based on microscopic tissue section pathology, with low-grade malignant tumors growing slowly, moderate-grade malignant tumors growing faster, and highly malignant tumors called glioblastomas, which are The most common adult malignant brain tumor with very fast growth rate. Oligodendroglioblastoma —- accounts for about 4% of all brain tumors. It spreads in a similar manner to astrocytoma and is usually not curable by surgery. Ventricular meningioma —- accounts for about 2% of all brain tumors. This tumor is derived from ventricular meningeal cells, and because it does not spread into 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 are seizures, memory loss, physical weakness, difficulty with limb control, 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 tissue is 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 the doctor suspects that the patient has a brain tumor, or if the patient has persistent headaches and severe symptoms (such as seizures), cranial imaging, including CT or MRI, is required. If the examination suggests a cranial tumor, a pathological biopsy will be performed to diagnose malignant glioma.
3. How is glioma graded?
Gliomas can be classified into various subtypes according to their different characteristics. The grading of tumors reflects the morphology of tumor cells under the microscope, the speed of abnormal cell growth and metastasis. grade I tumors grow more slowly and can usually be removed surgically, while grade IV tumors grow rapidly and are highly invasive, making treatment difficult.
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, meaning glioblastoma multiforme (GBM), and at least 80% of malignant gliomas are glioblastoma multiforme, which are considered highly malignant.
Oligodendroglioblastoma tumors are graded as follows.
Grade 2 or low-grade malignant oligodendroglioma
Grade 3 or highly malignant oligodendroglial cell tumor
Ventricular meningeal tumors are classified as ventricular meningiomas and mesenchymal ventricular meningiomas (which are more aggressive).
Low malignant tumors are usually slow growing, but may change to highly malignant tumors over time.
Principles of treatment for glioma
Depending on the location of tumor growth, histological typing and malignancy classification, there are different treatments available for malignant glioma. The patient’s age and physical condition also limit the treatment plan to some extent. There are more treatment options for glioma, which can be broadly summarized as follows.
1. Surgical removal of the tumor is the primary treatment, which of course requires that the patient’s other organs function relatively well and that the surgery should preserve the language and behavioral functions of the brain as much as possible. Imaging techniques such as PET scans and functional MRI scans can help to preserve the function of the tumor during the surgery. 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 headache or neurological symptoms by reducing brain edema caused by tumor, and antiepileptic drugs are used to control or prevent seizures.
Treatment of low-grade malignant astrocytoma
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 intertwine with normal brain tissue, making surgery sometimes difficult.
Treatment of highly malignant astrocytoma
Highly malignant astrocytomas (grade III mesenchymal astrocytoma or grade IV glioblastoma multiforme) can still be considered for surgical treatment if feasible, although surgical treatment is no longer curative. After surgery, the next step is radiation therapy, combined with chemotherapy. In some cases, surgery is considered impossible 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.
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 radiotherapy is usually used.
Treatment of ventricular meningioma and mesenchymal ventricular meningioma
Ventricular meningiomas and mesenchymal ventricular meningiomas differ from other gliomas in that they 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.
IX. Prognosis of glioma
Gliomas with high malignancy grow very rapidly, they cannot be cured, and the prognosis is usually poor, especially for elderly patients with brain tumors. In a very small number of patients with 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.