Glioblastoma is a primary malignant tumor of the central nervous system responsible for the majority of deaths among patients with primary brain tumors. It can occur in the brain or in the spinal cord and is highly invasive, and its most striking feature is the potential for infiltration into the surrounding brain parenchyma, typically remaining confined to the central nervous system (CNS). It forms from cells called astrocytes, which support and nourish the nerve cells (neurons) in the brain.
Although this tumor grows quickly in the brain, it rarely spreads to other parts of the body.
In a WHO (World Health Organization) classification of I to IV, IV being the most aggressive, glioblastoma is classified as grade IV. Currently, this classification has been updated, starting to incorporate molecular findings present in the tumor to characteristic histological findings.
The risk factors for the emergence of glioblastoma are poorly understood. Like other types of cancer, it starts when cells grow out of control and form tumors. Less than 1% of glioblastomas may be associated with hereditary cancer syndrome, including neurofibromatosis types 1 and 2, Turcot syndrome, and Li Fraumeni syndrome.
Usually, glioblastoma can arise from a transformation of a grade II or III astrocytoma. Ionizing radiation is the only known external risk factor for the development of glioblastoma.
Symptoms of glioblastoma
Some of the symptoms of glioblastoma are related to the location of the tumor. For example, if it grows up in an area that controls arm movements, the limb may lose strength. If it grows up in an area that controls speech, the ability to communicate verbally can be affected.
As the tumor continues to grow, it starts to take up space. This increases pressure within the brain, which leads to symptoms such as:
- Difficulty learning;
- Loss of appetite;
- Loss of balance or difficulty walking;
- Mood swings;
- Nausea and/or vomiting;
- Behavior changes;
- Problems speaking;
- Memory problems;
- Difficulty concentrating;
- Changes in vision.
Diagnosis of glioblastoma
At the clinical consultation, after taking a history and physical examination, the doctor will order additional tests that may include:
- Computed tomography (CT) – this is usually the first to be performed when the patient is taken to the emergency room with symptoms. With CT, it is possible to find areas suggestive of the presence of a tumor, assess areas of recent bleeding and calcifications;
- Magnetic resonance imaging (MRI) – ideal for evaluating typical glioblastoma findings through imaging as it can help define tumor location, tumor-related areas of edema, and areas of ischemia. Typical MRI findings usually differentiate glioblastoma from other pathologies such as abscesses, primary central nervous system lymphomas and metastases from non-primary brain tumors. In addition, they help in the assessment of the degree of resection after surgical treatment and in the assessment of the response to radiotherapy and chemotherapy, as well as in the follow-up of the disease;
- Biopsy/Surgery – the diagnosis of glioblastoma is made by removing tumor fragments for histological and molecular analysis. This evaluation can be done by biopsy, when only small samples of the tumor are removed for analysis, or by surgical resection of the tumor, when it is intended to remove a large part of the tumor or resect it almost completely. After the removal of the tumor and/or its fragments, the material is evaluated by a medical neuropathologist who focuses on histology, immunohistochemistry and, sometimes, molecular tests present in the tumor to close the diagnosis of glioblastoma.
The treatment of glioblastoma encompasses a multidisciplinary medical team with neurosurgeons, oncologists, radio-oncologists and neurologists, in addition to essential professionals for parallel procedures, such as physiotherapists, occupational therapists, speech therapists, nutritionists and psychologists.
The choice of protocol will depend on age, the general health of the patient and the size and location of the tumor at the time of diagnosis.
In general, the standard treatment for glioblastoma usually involves surgery followed by chemotherapy and radiotherapy, always associated with supportive clinical care.
Surgery is used to remove as much of the tumor as possible, preserving the patient’s functions. Resection of a visible part or all of the tumor can help relieve pressure on the brain, decreasing symptoms and improving quality of life, as well as providing data for the histological and molecular diagnosis of the disease.
Even with the best surgical techniques, some tumor cells may remain. Therefore, after the surgical procedure, it is recommended to complement the treatment with chemotherapy, radiotherapy, drugs to reduce cerebral edema and seizures, and palliative support clinical care.
After completion of the indicated treatment, the patient will be monitored by the multidisciplinary medical team, performing imaging tests and periodic consultations.
Because it is not caused by controllable factors, glioblastoma is not a preventable disease.