Adult Brain Tumours
Tumours of the brain may affect people of any age. There are a wide range of tumours that occur in or around the brain. Tumours of the brain that occur in children tend to be quite different in nature and are considered separately. Tumours can also occur from the structures around the brain such as the meninges. The most common example would be a meningioma.
Tumours from other sites also often metastasise to the brain and may require treatment. In some cases, symptoms from a cerebral metastasis will be the first sign of any tumour. Common tumours to metastasise to the brain include melanoma, lung cancer and breast cancer.
The most common tumour of the brain that arises from the brain itself is a glioma. Tumours of the brain are graded using a World Health Organisation (WHO) grading system from I to IV with grade IV being the most aggressive. Unfortunately, the majority, but certainly not all, tumours that arise in the brain of adults are grade IV tumours. These tumours are often referred to as glioblastoma multiforme (GBM).
Lower grade tumours also occur and may be WHO grade II or III tumours. These however can still cause symptoms and can change in nature to become grade IV tumours or GBM.
What symptoms do brain tumours cause?
The symptoms will depend on the nature of the tumour as well the location of the tumour. There are broadly three categories of symptoms.
How are brain tumours diagnosed?
The main method used to diagnose a tumour is a CT scan or MRI scan of the brain. The use of contrast for a CT or gadolinium with an MRI will assist in the diagnosis as many tumours will enhance with contrast or gadolinium.
While many tumours have a characteristic appearance particularly on an MRI scan, the diagnosis must be confirmed using histology. The histological diagnosis is the important diagnosis and relies on a sample of tissue being obtained either through a biopsy or through surgical resection. The tissue is then examined by the pathologist under a microscope to obtain the diagnosis. Additional tests for genetic mutations of the tumour are now routinely performed on most tumours.
The histological diagnosis will not only provide the type of tumour but will also provide a grade of the tumour. The histological diagnosis will provide important prognostic information and will also provide guidance in terms of the other treatments that may be required.
What is the management of a brain tumour?
The aim of the surgery is to:
1. Relieve the patient’s symptoms, and in some cases, this may need to be performed on an urgent basis. This will often relieve any raised intracranial pressure.
2. Obtain a histological diagnosis
3. Resect the tumour to provide optimal outcome in terms of neurological function and survival.
While surgical resection is the most appropriate treatment for most tumours, in some cases a biopsy may be the safest and or most appropriate option. This involves a smaller procedure where a burr hole is performed, and a needle is passed through the brain and into the tumour to obtain several small pieces of tissue in order to confirm the histological diagnosis and direct further treatment.
What happens after surgery?
Initial management will depend on the patient’s symptoms. Patients with evidence of oedema and/or raised intracranial pressure are normally administered a steroid called dexamethasone. This is normally continued through any surgery and then slowly weaned after surgery. It may also be used during radiotherapy.
Most tumours, depending on their location, will be managed by surgical resection. Surgical resection is normally performed using a craniotomy. The surgery is assisted by the use of an image guidance system that uses stereotaxy to guide the surgery allowing a smaller incision and craniotomy to be performed and guiding the surgeon to the lesion. A craniotomy is a surgical opening in the skull to allow access to the tumour. The bone is then replaced at the end of the operation and secured to the surrounding skull using small titanium plates. Various types of craniotomies can be performed depending on the location and size of the tumour.
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Depending on the histological diagnosis, further treatment may be indicated. For a GBM, surgery is normally followed a few weeks later by radiotherapy and a tablet form of chemotherapy called temozolomide. The radiotherapy is delivered on a daily basis over a 6-week period. These doses are called fractions. Normally 30 fractions are delivered over the 6-week period with the patient also taking temozolomide. The temozolomide is normally also continued for 1 week per month during the 6 months following radiotherapy.
Patients having undergone treatment for a brain tumour are also monitored using MRI scans after surgery. Apart from the standard 6-week post-operative visit with Prof Owler, the patient is also monitored by the oncologists providing treatment. Following radiotherapy, MRI scans are normally performed every 3 months. Shortly after the MRI scan the patient and their scans are reviewed by Prof Owler.
This treatment paradigm is based on standard treatment of GBM which is the most common adult brain tumour. However, there are numerous other tumours which to which this treatment may not apply. The treatment is always tailored to the individual patients and their needs.