Brain Cancer and Gliomas
How Are Gliomas Diagnosed?
If a brain tumor is suspected, a brain scan is typically done. This includes a CT scan, an MRI scan (considered to be superior), or both. If the brain scan suggests a brain tumor, a biopsy is performed for diagnosis. A biopsy may be performed as a separate procedure or at the time the tumor is removed if surgery is a treatment option.
How Are Gliomas Graded?
Gliomas are characterized by subtypes and by a numerical grading system. The grade of a tumor means how the cancer cells appear under a microscope. Grade I tumors grow slowly and are often removed by surgery, while grade IV tumors are fast-growing, aggressive, and difficult to treat.
According to the 2000 World Health Organization (WHO) scheme, perhaps the most widely accepted approach to tumor classification, malignant gliomas are classified and graded as follows:
- Grade I gliomas are called gilocytic astrocytomas and are usually seen in children.
- Grade II tumors are called diffuse fibrillary astrocytomas and are low grade.
- Grade III gliomas are called anaplastic astrocytoma. They're considered high grade.
- Grade IV glioblastoma (glioblastoma multiforme, GBM). (At least 80% of malignant gliomas are glioblastoma multiforme or GBMs.) These are considered high grade.
The oligodendroglial tumors are classified as follows:
- Grade II or low grade oligodendroglioma
- Grade III or high grade oligodendroglioma.
The ependymal tumors are classified as ependymoma and anaplastic ependymoma with the latter being more aggressive.
The low-grade tumors usually grow slowly but may transform into high-grade tumors with time.
How Are Gliomas Treated?
Different treatment options are considered for malignant glioma, depending on the location of the tumor, type of glioma (cell type), and grade of malignancy. The patient’s age and physical condition also play a role in determining treatment. Treatment for gliomas is multifaceted and may include:
- Tumor removal by surgery is the mainstay of treatment. The patient should be otherwise relatively healthy, and brain function, speech, and mobility is able to be maintained. Imaging techniques such as CT scanning and functional MRI may be used to assist the surgeon in removing the tumor. The goal is to remove as much of the tumor as possible and obtain an accurate diagnosis. Recurrences of the tumor are frequent.
- Radiation therapy uses high-energy X-rays or other radiation to kill the cancer cells.
- Chemotherapy uses drugs to stop the cancer cell growth. This therapy may be taken by mouth or injected.
- Supportive therapy to improve symptoms and neurologic function include corticosteroids to reduce swelling in the brain caused by the tumor and anticonvulsants to control or prevent seizures.
- Clinical trials, performed to see if new cancer therapies are effective and safe, are another option.
Treatment for Low-Grade Astrocytomas
The treatment for low-grade astrocytomas is surgery. However, because these tumors penetrate deep into the brain and grow into normal brain tissue, surgery is sometimes difficult. If surgery is not an option or if the tumor can't be completely removed, radiation is used. These tumors are thought to be resistant to chemotherapy.