27 Jul, 2023
Glioblastoma is an aggressive and fast-growing brain tumor. It was previously called ‘glioblastoma multiforme’ (GBM) and the name is often found in use even now. It may invade the surrounding brain tissues but usually does not metastasize to distant organs. In some cases, it can spread to more than one site within the brain. Glial cells are affected by glioblastoma. These cells are essential for nerve cell function.
The most common sites of glioblastoma in adults are the temporal lobe and frontal lobe of the cerebral hemisphere. Glioblastoma, if left untreated, progresses very rapidly, with only a few months of survival. Even if all modalities of treatment are not offered, the benefit or survival rate reduces as compared to when all treatments are offered, including surgery, radiation, and chemotherapy.
Glioblastoma is one of the most common malignant primary brain tumors. The annual incidence of this disease ranges from 0.5 to 5 per 100,000, and the incidence is increasing in several countries. Though the reasons are not very well established, some causative factors are known to increase incidence, including an aging population, air pollution, radiofrequency electromagnetic fields (RF-EMF), ionizing radiation, and smoking.
Morphologically, the World Health Organization classifies brain tumors from 1 to 4. Grade 1 tumors are the least aggressive, while grade 4 tumors are highly aggressive. Grade 1 tumors are benign, while grade 2 tumors are relatively benign. Grade 3 tumors are low-malignant tumors, and grade 4 tumors are aggressive malignant tumors. Glioblastoma tumors are classified as grade 4 tumors.
These tumors may be either primary or secondary. The primary glioblastoma type originates directly from the glial cells. However, in some cases, lower-grade tumor cells transform into glioblastoma cells. It is known as secondary glioblastoma.
The glioblastoma diagnosis can be made through the following process:
The symptoms depend upon the location of the tumor and its size. Because glioblastoma is a rapidly growing tumor, the symptoms are of short duration (over days or weeks) and progress rapidly. Depending on the location, a patient could present with seizures (fits), altered behavior or personality, drowsiness, weakness in a part or one half of the body, hearing, speech, vision, memory, or other symptoms. Many times, headaches, nausea, or vomiting might be the only symptoms.
Thus, it is important to consult with neuro-oncologists and neurosurgeons if patients experience any neurologic symptoms.
Patients with any neurologic symptoms should visit the neurologists for a comprehensive evaluation. It is important to rule out other diseases, such as infection or inflammation, as they also cause symptoms similar to those of glioblastoma. Neurologists should also consider differential diagnosis for other complex conditions, such as primary CNS lymphoma, intracranial hemorrhage, oligodendroglioma, or other brain tumors, toxoplasmosis, or other infections, and rarely, radiation necrosis (if the patient has a previous history of radiation to the brain).
Several imaging tests are performed to determine the presence and severity of glioblastoma. These imaging tests include:
It might often be the first test done by a neurologist. This test would show glioblastoma as an irregularly shaped hypodense lesion with central necrosis and thick margins. It could also help differentiate and rule out other diseases which have a different appearance radiologically.
Conventional MRI is the imaging of choice for brain tumors; it is best performed with a contrast agent. Conventional MRI also provides important information related to the grade of the brain tumor, brain swelling, infiltration, and tissue cellularity. The lesion of glioblastoma shows certain very distinct features as compared to other tumors.
Functional MRI provides useful information about the parts of the brain that are activated when the patient is asked to perform certain activities, such as the movement of a leg or hand. Functional MRI helps in planning the surgery in cases where the glioblastoma (tumor) is located near critical areas of the brain.
In the case of a single brain lesion, it’s important to evaluate if any other site in the body has the disease, which could indicate if the brain lesion is a primary brain lesion or a metastasis from any other site of disease. A functional PET-CT also helps in follow-up cases post-radiation to differentiate between tumor recurrence and post-treatment changes. This, in turn, helps decide on further treatment.
This technique is based on MRI. It provides important information about the chemical composition of tumors. Certain chemicals are abundant in healthy brains, while others are abundant in tumors, such as choline. The levels of these chemicals indicate disease, other reasons, or post-treatment changes. This technique involves non-invasive tissue sampling and is less definitive and accurate than a standard biopsy, but it is very useful in differentiating tumors from post-treatment changes in the brain.
A histopathological examination is performed on the intra-operatively removed tumor for a definitive diagnosis. If the tumor is not suitable for surgery due to the location of the tumor, a stereotactic biopsy is an alternative. The analysis involves determining the absence or presence of Glial Fibrillary Acidic Protein (GFAP), O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status, and isocitrate dehydrogenase (IDH) mutation status, ATRX among other tests.
Some of the treatment options for GBM tumors are:
The aim of the surgery in patients with GM tumors is to remove the tumor as much as possible without causing injury to the surrounding healthy tissues of the brain. Depending on tumor location, oftentimes residual disease is expected or seen on post-op MRI. Debulking the tumor with surgery improves the quality of life and prolongs it in some patients. Awake craniotomy is an increasingly used technique to reduce the risk of neurologic damage.
Radiation therapy involves delivering prespecified doses of radiation to the tumor to prevent recurrence. The usual radiation dose is different for different tumors. It is preferable to deliver radiation over a period of six weeks with concurrent oral chemotherapy tablets (Temozolomide).
For patients with poor performance status or ages > 70, a shorter protocol of three weeks of radiation is recommended. The most common techniques of radiation therapy include IMRT (intensity-modulated radiation therapy), IGRT (image-guided radiation therapy), and VMAT (volumetric modulated arc therapy). These techniques help minimize doses to normal organs as compared to older techniques.
Its use in glioblastoma is restricted to recurrences. It is one of the most advanced techniques for delivering radiation therapy. During this procedure, the goal is to minimize the harmful effect of radiation on healthy brain cells by delivering highly focused radiation to the tumor over 3-5 sessions.
The chemotherapy of choice is Temozolomide tablets given with radiation and also post-treatment. It’s given with stringent monitoring of blood investigations and under supervision. Studies have reported improved survival in patients receiving radiation therapy and chemotherapy simultaneously.
This therapy involves delivering a low-intensity electric field to the tumor with the help of electrodes on the scalp. TTF therapy prevents or delays the growth and division of cancer cells. It is usually used after the completion of chemotherapy and radiation therapy. Currently, its availability is restricted to only a few countries. It improves survival by a few weeks when combined with the other treatments.
Individuals should not ignore any symptoms. Patients should book an appointment when they experience the symptoms listed above. While it may be due to non-cancerous reasons in most situations, one needs to be prompt for early diagnosis and treatment of any neurologic issues, be they cancerous or non-cancerous.
Glioblastoma is a condition that originates in the glial cells of the brain. There is a rapid progression of glioblastoma characterized by several symptoms, such as headache, weakness, vision changes, personality changes, and various other symptoms. There is very little understanding of the exact cause of glioblastoma. Glioblastoma diagnosis is made through various imaging techniques, such as CT scans, MRIs, PET scans, and MRI spectroscopy. The definitive diagnosis is made through a biopsy. The commonly recommended treatments include surgery, radiation therapy, and chemotherapy.
Frequently Asked Questions
The aggressive nature of glioblastoma makes it one of the worst cancers to be diagnosed with. Often, the rapid progression of glioblastoma makes survival very short if not treated. Also, due to its aggressive nature, long-term survival or cure is not achievable with the current modalities of treatment available for its use.
There is no cure for glioblastoma. Although the life of a patient can be prolonged with advanced medical interventions, the disease is almost always fatal.
Glioblastomas are fatal, and the median survival period after diagnosis is about 14 months. Only 3 to 5% of the patients survive over three years, while only 2% survive over five years.
There is a high growth rate of glioblastoma in the brain. A study reported that these cells can grow 1.4% in a day. The growth occurs at a microscopic level. The median time in which the tumor size doubles is about seven weeks.
Glioblastoma tumors are rapidly dividing and invading other brain tissues locally or in the form of skin lesions. However, they rarely metastasize to other body organs.
Studies suggest that most are sporadic and not genetic. Only about 5% of the cases have a genetic association and are present in two or more family members.
There are no foods that prevent the occurrence of glioblastoma multiforme.