A malignant glioma is a type of primary brain cancer, meaning it originates within the brain tissue. These tumors arise from glial cells, the most abundant cell type in the central nervous system. The term “malignant” signifies that the tumor is cancerous and characterized by rapid, invasive growth. This aggressive nature allows the tumors to interfere with normal brain function.
Understanding Malignant Gliomas
Glial cells provide support and protection for neurons. Different types of gliomas originate from specific glial cells. Astrocytes, star-shaped cells that nourish neurons, can give rise to astrocytomas, while oligodendrocytes, which produce the myelin sheath that insulates nerve fibers, form oligodendrogliomas. Malignant gliomas are the more aggressive forms of these tumors, including anaplastic astrocytoma and anaplastic oligodendroglioma. The most common and aggressive type is glioblastoma, which develops from astrocytes.
To classify severity, medical professionals use a grading system from the World Health Organization (WHO). Malignant gliomas are categorized as high-grade (Grade III or IV), reflecting their rapid growth and infiltration of surrounding brain tissue. Modern classification also involves analyzing the tumor’s molecular characteristics. Two molecular markers are the IDH mutation status and MGMT promoter methylation. The presence of an IDH mutation can be associated with a more favorable outcome, while MGMT promoter methylation predicts how well the tumor might respond to certain chemotherapy.
Recognizing the Symptoms
The signs and symptoms of a malignant glioma depend on the tumor’s size and location within the brain. As the tumor grows, it can increase pressure inside the skull, leading to general symptoms. These include persistent headaches that may worsen with activity, unexplained nausea and vomiting, and increasing drowsiness or confusion.
Other symptoms are localized to the functions controlled by the affected brain region. A tumor in the frontal lobe, for instance, might cause personality or mood changes, while one in the temporal lobe could lead to memory problems or seizures. A glioma in the cerebrum can cause weakness on one side of the body, speech difficulties, or vision disturbances.
The Diagnostic Process
The diagnostic process for a malignant glioma begins with a neurological examination. A physician will assess a patient’s reflexes, coordination, muscle strength, sensory perception, and cognitive functions. Following the exam, imaging tests are ordered to visualize the brain.
Magnetic resonance imaging (MRI) with a contrast agent is the primary tool used to detect a glioma, providing detailed images of its size, shape, and location. Computed tomography (CT) scans may also be used, though they are less sensitive than MRI for these tumors.
While imaging provides strong evidence, a definitive diagnosis requires a biopsy. A neurosurgeon removes a small sample of the tumor tissue for a pathologist to examine. This examination confirms the glioma, determines its type and grade, and tests for molecular markers like IDH and MGMT status.
Current Treatment Approaches
Treating malignant gliomas involves a combination of therapies tailored to the patient. Surgery is often the first step, with the goal of “maximal safe resection,” meaning the neurosurgeon removes as much of the tumor as possible without harming brain tissue responsible for functions. Because these tumors are invasive, complete removal is difficult.
After surgery, radiation therapy is administered to target any remaining cancer cells using high-energy beams focused on the tumor site. Concurrently, or following radiation, patients receive chemotherapy. The most common drug for high-grade gliomas is temozolomide (Temodar), which damages the DNA of cancer cells to stop their growth.
Newer options are also available. Tumor Treating Fields (TTFields) use electrical fields from a wearable device to disrupt cancer cell division. Targeted therapies are drugs designed to work on specific molecular characteristics in the tumor cells, and clinical trials may offer access to other innovative treatments.
Treatment Outcomes and Management
The goal of treatment is to slow the tumor’s progression, manage symptoms, and maintain the patient’s quality of life. Several factors influence a patient’s outcome, including:
- The tumor’s grade
- The patient’s age and overall health
- How much of the tumor was removed during surgery
- The presence of favorable molecular markers like an IDH mutation
High-grade gliomas have a more challenging prognosis due to their aggressive nature and high rate of recurrence. Low-grade gliomas have a more favorable outlook, particularly when complete surgical removal is possible.
A multidisciplinary care team supports patients and their families through treatment. This team includes:
- Neuro-oncologists
- Neurosurgeons
- Radiation oncologists
- Nurses
- Social workers
Palliative care is also a component of the management plan. It focuses on providing relief from the symptoms and stress of the illness to improve quality of life for the patient and their family.