The best treatment for glioblastoma currently is surgery to remove as much of the tumour as possible, followed by a combination of chemotherapy and radiotherapy.
Surgery for glioblastoma
Your surgeon will try to remove as much of the tumour as possible. This is known as debulking.
With glioblastomas it can be difficult to remove the whole tumour because:
- they are diffuse, this means they have threadlike elements that spread out into the brain
- it can be hard to tell the difference between the edges of the main part of the tumour and normal brain tissue.
This means that parts of the tumour may get left behind after surgery.
The extent to which the tumour can be safely removed will also depend on its location in the brain, i.e. how deep in the brain it is and whether it's near to any important parts of the brain.
Before surgery, you may like to ask about biobanking some of the tissue from your tumour. Doing this may enable you to be a candidate for certain clinical trials in the future and also have any relevant genetic (biomarker) tests.
Treating glioblastoma with chemoradiation
Chemoradiation comprises radiotherapy over a period of weeks along with rounds of the chemotherapy drug temozolomide (TMZ). It is used to slow the growth of any tumour cells that cannot be removed by surgery.
Temozolomide works by stopping tumour cells from making new DNA (the material that carries all their genetic information). If they cannot make DNA, they cannot divide into new tumour cells, so the tumour cannot grow. It is also thought to make the tumour cells more sensitive to the radiation.
Temozolomide is usually taken for a further six months after radiotherapy finishes.
Gliadel® wafers are small wafers, coated with the chemotherapy drug carmustine, that are put directly into the brain at the end of surgery. This means the treatment gets round the blood-brain barrier that prevents many chemotherapy drugs from entering the brain.
The wafers are only licensed in the UK for use in recurrent glioblastomas (glioblastomas that have come back) and when the surgeon is confident that at least 90% of the tumour has been removed. Find out more about chemotherapy.
Effectiveness of treatment
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.
You may have heard that the use of another drug, called
bevacizumab (Avastin®), may be helpful in the treatment of glioblastomas. However, in Europe it is felt that there is insufficient evidence for its effect on brain tumours and for this reason it is not licensed for use with brain tumours in the UK.