Glioblastoma is the most aggressive form of cancer that starts with brain and typically kills 90 percent of its sufferers within about two years. In simple terms, once a person is diagnosed; life expectancy is not expected to go beyond 16-18 months.
John Mccain died 25th August 2018 after succumbing to Glioblastoma, a type of brain cancer he was diagnosed with in July 2017. This came days after it was reported he chose to discontinue his treatment. Other notable personalities who have succumbed to this same disease are Ted Kennedy and Joe Biden’s son Beau.
Glioblastomas are the most common high grade (cancerous) primary brain tumour in adults. They can also occur, though rarely, in children. They belong to a group of brain tumours known as gliomas, as they grow from a type of brain cell called a glial cell.
Glioblastoma are ‘diffuse’, meaning they have threadlike tendrils that extend into other parts of the brain. They are fast growing and likely to spread. You may also hear them called glioblastoma multiforme, GBM or GBM4.
There are different types of glioblastoma:
- Primary – this means the tumour first appeared as a grade 4 glioblastoma (GBM)
- Secondary – this means the tumour developed from a lower grade astrocytoma
Nobody yet knows what causes glioblastoma, however they can either start from normal brain cells or develop from an existing low-grade astrocytoma and accounts for 15% of all brain tumors.
It affects the glial cells, which are some of the most important cells in the brain (though some neuroscientists argue they are the most important).
Glial cells make up 90 percent of the brain. They encapsulate and insulate the neurons, which transmit messages and make everything function. That is what earned them the name when they were discovered in the 1800s (‘glial’ is Greek for ‘glue’).
At the time, neuroscientists were focused on the all-important neurons, seeing glial cells as essentially a sticky blanket. For that reason, research into them didn’t get going until the 1960s.
Glioblastoma tumors don’t spread to other organs, but it is nearly impossible to locate how far it has seeped across the brain. Unlike other types of brain cancer which are more specifically located, glioblastoma can occur in any part of the brain.
Because the tumor has likely already spread deep into the brain by the time it is diagnosed, the cancerous tissue is incredibly difficult to remove. It is most commonly found in men aged 50 to 60, and there is no link between developing glioblastoma and having a previous history with other types of cancer.
Even though causes are unclear; as with most cancers, 2 risk factors are probable;
- Genetics: uncommon risk factors include genetic disorders such as neurofibromatosis, Li–Fraumeni syndrome, tuberous sclerosis, or Turcot syndrome. Previous radiation therapy is also a risk. For unknown reasons, GBM occurs more commonly in males.
- Environmental: other associations include exposure to smoking, pesticides, and working in petroleum refining or rubber manufacturing.
Symptoms vary from person to person and are mostly non-specific. Which makes it difficult to diagnose. However, common complains are;
- confused vision
- trouble with memory
A lot of times, sufferers are unaware they have the tumor until they start to have seizures; because of the pressure caused by the tumor being so close to neurons, the cells that tell the rest of the body what to do. At this point, diagnosis is easily effective.
The best treatment currently is surgery to remove as much of the tumour as possible, followed by chemoradiation to target cells which cannot be removed by surgery. This is a combination of chemotherapy and radiotherapy.
Generally, it involves radiotherapy given over a period of weeks alongside rounds of the chemotherapy drug temozolomide (TMZ). TMZ is also usually taken for a further 6 months after the radiotherapy has finished. Before surgery, you might like to ask about the possibility of biobanking a sample of tissue from your tumour. This may enable you to take part in clinical trials in the future and also have any relevant genetic (biomarker) tests.
Unfortunately glioblastomas are aggressive tumours and often appear resistant to treatment. This is probably due to the fact that the cells within the tumour are not all of the same type. This is known as ‘heterogeneity’. This means that treatments will kill off some types of cell within the glioblastoma, but leave others, which can then continue to grow.
However, some of the research into the genes, which play a role in glioblastoma (GBM) development and growth, are starting to give us information about who may respond better to certain treatments. For example biomarker tests, such as:
- MGMT gene methylation test
This shows how likely you are to respond to the chemotherapy drug, temozolomide.
- Mutations in the IDH-1 and TERT gene
These mutations are associated with effects on overall survival.
Many centres routinely test for these gene mutations, but if your hospital does not and you would like to have a test, ask your neuro-oncologist for information and advice about whether you are suitable.