Gliomas are tumors that originate in the brain or spinal cord from supportive cells known as glial cells. These tumors can be slow-growing or aggressive, representing a significant portion of all brain and central nervous system tumors. This article covers their types, symptoms, diagnosis, and treatment.
What Are Gliomas?
Gliomas are tumors that develop from glial cells, which are non-neuronal cells found in the central nervous system. Glial cells play a supportive role for neurons, providing nutrients, insulation, and structural support. When these cells grow uncontrollably, they form a glioma.
These are primary brain tumors, originating directly within brain tissue. Gliomas primarily affect the brain but can also occur in the spinal cord. Their growth can press on surrounding brain or spinal cord tissue, leading to various symptoms.
Types and Grading
Gliomas are categorized based on the specific type of glial cell from which they originate. The main types include astrocytomas (from astrocytes), oligodendrogliomas (from oligodendrocytes), and ependymomas (from ependymal cells). Astrocytomas are the most common type of glioma, with glioblastoma multiforme (GBM) being a particularly aggressive form.
The World Health Organization (WHO) classifies gliomas using a grading system from I to IV, indicating the tumor’s aggressiveness and growth rate. Grade I tumors, such as pilocytic astrocytomas, are generally slow-growing and may sometimes be cured with surgery. Grade II gliomas are relatively slow-growing but can spread into normal tissue and may recur as higher-grade tumors over time.
Grade III gliomas, often referred to as anaplastic, are malignant with rapidly dividing abnormal cells that can spread into nearby brain tissue. Grade IV gliomas, including glioblastoma, are the most aggressive and fast-growing, often forming new blood vessels to sustain their rapid growth and containing areas of dead tissue. The WHO 2021 classification also incorporates molecular markers, such as IDH mutations, which influence tumor behavior and prognosis.
Recognizing Symptoms
The symptoms of a glioma can vary widely depending on the tumor’s size, location, and rate of growth. Common general symptoms include headaches (particularly those that worsen in the morning), and unexplained nausea and vomiting. Seizures are also a frequent symptom, especially in individuals with no prior history.
Gliomas can also cause specific neurological symptoms based on the affected brain region. For example, a tumor in the frontal lobe might lead to personality changes or irritability, while one in the occipital lobe could cause vision problems like blurred or double vision. Difficulties with speech, memory loss, confusion, or problems with balance and coordination can also occur. Spinal cord gliomas can result in pain, weakness, or numbness in the limbs.
Diagnostic Approaches
Diagnosing a glioma begins with a thorough medical history and a neurological examination. This assesses functions such as vision, hearing, balance, coordination, strength, and reflexes, providing clues about affected brain or spinal cord areas. Swelling of the optic nerve, known as papilledema, indicates increased pressure within the skull.
Imaging techniques are fundamental for identifying and characterizing the tumor. Magnetic Resonance Imaging (MRI) is the most frequently used imaging test, providing detailed images of the brain. A contrast dye is sometimes injected to enhance tumor visibility. Computed Tomography (CT) scans may also be used, especially as an initial quick assessment or if an MRI is not feasible.
The definitive diagnosis of a glioma requires a biopsy, where a tissue sample is obtained for laboratory analysis. This sample is examined by a pathologist to determine the exact type of glioma, its grade, and specific genetic mutations, which are important for guiding treatment decisions. In cases where surgical removal of the tumor is not an immediate option, a stereotactic needle biopsy, guided by imaging, may be performed.
Treatment Strategies
Treatment for gliomas is highly individualized, taking into account the tumor’s type, grade, location, and the patient’s overall health. Surgical resection, or tumor removal, is a primary approach, aiming to remove as much of the tumor as safely possible. Even partial removal can help alleviate symptoms by reducing pressure on brain tissue.
Radiation therapy is frequently used, often after surgery, to destroy remaining cancer cells. This can involve external beam radiation, where high-energy rays are directed at the tumor, or advanced techniques like proton therapy, which precisely target the tumor while minimizing exposure to healthy tissue.
Chemotherapy, using drugs to kill cancer cells, is another common treatment modality. Temozolomide is a chemotherapy drug often used concurrently with radiation therapy and as an adjuvant treatment for certain gliomas.
Targeted therapies represent a newer approach, focusing on specific molecular characteristics of the tumor cells, such as gene mutations, to inhibit their growth. For instance, vorasidenib has been approved for certain low-grade diffuse gliomas with IDH gene mutations. Patients may also be eligible for clinical trials, which investigate new and experimental treatments, including novel surgical methods, radiation techniques, or systemic therapies like immunotherapy.