What is a meningioma?
Meningioma is the most common form of adult primary brain tumour, that develops in the meninges – the membrane that surrounds the brain and spinal cord. Meningiomas account for approximately 30-37% of all adult central nervous system tumours. Most are low-grade (non-cancerous) primary brain tumours.
A primary brain tumour means that the first site of occurrence is in or around the brain, rather than being a secondary occurrence resulting from another form of cancer
What causes a meningioma?
The direct cause of a brain tumour is still not clear, so more investment in research is urgently needed. A patient’s personal medical history of genetic and lifestyle factors and in some cases, previous exposure to potential risk factors may help inform a diagnosis.
Previous radiotherapy to the head, for example to treat paediatric (childhood) cancer, may cause meningioma to develop a number of years after the initial treatment.
Meningioma can also occur as part of a genetic condition, Neurofibromatosis 2 (NF2).
The incidence of meningioma increases with age and there is a notable increase after the age of 65.
Meningioma are nearly twice as common in females than in males, rising to being three times more common in females between the ages of 35 and 54 years.
A drug called Cyproterone Acetate (CPA) that acts on testosterone and is used in the treatment a number of medical conditions. When used in very high doses, for example to control aggressive sexual disorders or support transgender women, CPA has been shown to induce meningioma. If the CPA is stopped, these tumours usually shrink and there is no need for any further treatment. It is therefore very important that you disclose to your medical team if you are taking CPA and have been diagnosed with a meningioma.
Estrogen-only hormone replacement therapy (HRT) has been linked to a small increased risk of developing a meningioma, but estrogen-progestin hormone therapy has not.
Are there different types of meningioma?
Approximately 80-90% meningiomas are grade 1 and slow-growing, but some are more aggressive, which is why medical teams ideally want to take a biopsy (a small sample taking during a surgical operation) of each tumour. This enables clinicians to classify the tumour both histologically (through a microscope) and using molecular profiling (studying the genetic characteristics of the tumour).
There are actually over 50 different sub groups of meningioma, but the World Health Organisation (WHO) groups them into three grades to reflect their main characteristics:
Grade 1 is the least aggressive and slowest growing form of meningioma, therefore carrying the longest prognosis. This form may never grow back after a successful surgical operation that is able to remove all, or most, of the tumour. Some meningioma may never grow any bigger and will not need to be treated at all, so the first line of response from your medical team may be to simply keep the tumour under close surveillance (for example by offering you a scan every 6 or 12 months), but not to treat until it poses a threat due to its size, position or a worsening of your symptoms.
Grade 2 meningiomas are known as “atypical meningioma.” Their name indicates the fact that these do not behave in a “typical” way and therefore their rate of growth and recurrence is hard to predict, but they are more likely to recur after surgery than a grade I meningioma. If you have a grade 2 meningioma you will be carefully monitored by your medical team to ensure that you receive the best possible care.
Grade 3 meningiomas are known as anaplastic (malignant) meningioma, and represent approximately 3% to 5% of those diagnosed. Unfortunately, these frequently recur after surgery, which is why they are also treated with radiotherapy.
How serious is a meningioma?
Meningiomas are typically slow-growing tumours that originate from the meninges, the protective covering around the brain and spinal cord. Most meningiomas are benign, meaning they are not cancerous, and they do not spread to other parts of the body. However, some meningiomas can become large and press on important structures in the brain or spinal cord, causing symptoms such as headaches, seizures, or changes in vision or hearing.The seriousness of a meningioma depends on several factors, including the size and location of the tumour, as well as the age and overall health of the patient. In general, smaller meningiomas that are not causing symptoms may not require immediate treatment, but larger or more aggressive tumours may require surgery, radiation therapy, or other forms of treatment.
It is important for anyone with a suspected or diagnosed meningioma to work closely with their healthcare provider to develop an individualized treatment plan and to closely monitor the tumour for any changes or signs of growth.
Molecular profiling of meningioma
Molecular profiling of meningioma can clarify the status of various genes, as well as the methylation profile of the tumour.
Methylation means adding, removing or replacing a methyl group (CH3) on a molecule (for example, DNA) that then influences the way in which molecules behave (for example, switching genes on the DNA on and off). Molecular profiling can potentially be used to predict which tumours are more likely to progress to a higher grade or recur after surgery, so there is a lot of research in this area at the moment to clarify which molecular markers can be relied upon to predict how a tumour will behave, and hence guide treatment decisions as well as offer opportunities to develop drugs that influence those molecules’ behaviour.
Higher grades of meningioma have larger numbers of genetic changes than lower grade tumours, which makes them more aggressive and harder to treat.
This knowledge helps medical teams to plan how aggressively they need to treat a tumour, or if it is safe to choose active monitoring: meaning regular scans and blood tests that will indicate when is the best time to treat. It also enables researchers to explore drugs that can target specific genetic mutations, leading in the future to more effective, personalised treatment protocols.
NF2 is the gene which when mutated gives rise to a condition called Neurofibromatosis 2, an inherited genetic disorder characterized by the development of schwannoma, ependymoma and meningioma tumours in the brain and spinal cord. Approximately 40% - 60% meningiomas have a mutation of the NF2 gene although this does not necessarily mean that the patient has Neurofibromatosis 2. If you were diagnosed with Neurofibromatosis 2 you would be directed to a specialist team to care for you.
What are the symptoms of meningioma?
Signs and symptoms of a meningioma may be quite subtle at first, only growing gradually and depending on where in the brain or (in rare instances) the spine the tumour is situated.
The signs and symptoms may include:
- Changes in vision, such as blurriness or seeing double
- Headaches that worsen with time
- Hearing loss or tinnitus (ringing in the ears)
- Memory loss
- Loss of smell
- Weakness in the arms or legs
Symptoms are primarily caused by the meningioma growing to a size that puts pressure on parts of the brain or spine nerves and blood vessels. This is especially true if the tumour is growing inwards rather than spreading close to the skull.
What is the survival rate of meningioma?
The survival rate for meningioma depends on various factors, such as the size and location of the tumour, the age and overall health of the patient, and the grade of the tumour. The grade of a meningioma refers to how abnormal the cells appear under a microscope, and it can range from grade I (benign) to grade III (malignant).In general, the prognosis for meningioma is usually good, especially for grade I tumours, which account for the majority of cases. According to the American Brain Tumour Association, the 5-year survival rate for grade I meningiomas is approximately 85-95%, and the 10-year survival rate is around 80-90%. For grade II meningiomas, the 5-year survival rate is around 65-75%, and the 10-year survival rate is around 50-60%. For grade III meningiomas, the survival rate is lower, with a 5-year survival rate of around 55-60%, and a 10-year survival rate of around 25-30%.
However, it is important to note that these are general statistics, and the prognosis for each individual case can vary significantly depending on the specific characteristics of the tumour and the patient's overall health. It is important for anyone with a meningioma to work closely with their healthcare provider to develop an individualized treatment plan and to closely monitor the tumour for any changes or signs of growth.
Can an MRI tell if a meningioma is benign?
An MRI can help in the diagnosis of meningiomas, but it cannot definitively determine whether a meningioma is benign or malignant. Meningiomas are typically slow-growing tumours that arise from the meninges, the protective covering around the brain and spinal cord. They can be classified as either benign (not cancerous) or malignant (cancerous), based on their appearance under a microscope.MRI (Magnetic Resonance Imaging) uses a magnetic field and radio waves to create detailed images of the brain and spinal cord. It can help in the diagnosis of meningiomas by providing information about the size, location, and characteristics of the tumour. MRI can also help to distinguish meningiomas from other types of brain tumours, such as gliomas or metastatic tumours.
However, a definitive diagnosis of a meningioma as either benign or malignant requires a biopsy, where a small sample of the tumour is removed and examined under a microscope by a pathologist. The pathologist will examine the tissue sample for characteristics that indicate whether the tumour is benign or malignant, such as cell size and shape, the presence of abnormal cell division, or the presence of necrosis (dead tissue).
In summary, an MRI can provide valuable information about the size and location of a meningioma, but a biopsy is required to definitively determine whether the tumour is benign or malignant.
What is the treatment for meningioma?
Treatment options are typically surgery and/or radiotherapy. Chemotherapy would normally be considered only for a high-grade meningioma.
Some meningiomas can be successfully removed by surgery, whilst others may be in positions that make complete removal impossible. For example, the tumour may be wrapped around the optic nerve or an artery. In these cases, the priority for the neurosurgeon will be to remove as much of the tumour as possible whilst avoiding damage to any critical structures within the brain.
If the tumour grows back, surgery may be offered again to reduce tumour size
After surgical removal, some meningiomas may grow back. For this reason, those classified as grade II or III will be treated with radiotherapy in order to reduce the risk of this re-growth happening.
Some tumours are treated with stereotactic radiosurgery, which is a tightly focused type of radiotherapy, usually given in one high-dose session. This is a contrast to the way in which fractionated radiotherapy is delivered, which is in lower doses spread over a number of appointments.
Chemotherapy is rarely used for meningioma tumours because they grow so slowly, and most chemotherapy drugs are designed to target cells that are dividing rapidly, as seen in more malignant (faster growing) forms of cancer.
More details about the current standard of care for meningioma can be found in the NICE guidance document here.
How will we find a cure for meningioma?
Research we are funding across all of our Centres of Excellence will help lead towards finding a cure.
Our University of Plymouth Low-Grade Brain Tumour Research Centre of Excellence is Europe’s leading research institution for low-grade brain tumours, and has a strong focus on meningioma. They have a large bank of meningioma samples and have identified a wide variety of genetic mutations across all grades. This has enabled them to develop a blood test that can identify different subgroups of meningioma, with the potential to be used as a way to classify and monitor tumours without the need for a surgical biopsy. They are also developing and testing a range of drugs for meningioma, including those caused by the genetic condition Neurofibromatosis 2 (NF2).
The team of research and clinical experts at our Centre of Excellence at Imperial College, London have built up a significant bank of meningioma tissue samples thanks to their close relationship with Charing Cross Hospital. They work closely with the University of Plymouth Centre of Excellence on certain aspects of research, particularly the identification of genes and proteins that can form potential targets for drugs to influence.
Scientists at our Centre of Excellence in the University of Portsmouth have identified a number of proteins that are expressed (activated) in Grade I meningioma, but are not expressed in healthy brain tumour cells. Such findings can potentially be used to develop treatments that target theses proteins and hence influence the processes that they control.
Pioneering research at our Brain Tumour Research Centre of Excellence at Queen Mary University of London has developed methods of studying stem cells that could potentially transfer across all types of brain tumour.
We also fund BRAIN UK at Southampton University, the country’s only national tissue bank providing crucial access to brain tumour samples for researchers from the archives of clinical neuroscience centres in the UK, effectively covering about 90% of the UK population, and an essential component in the fight to find a cure for meningioma.