Brain tumours often cause swelling in the brain and this swelling makes the pressure effect of the brain tumour worse. Symptoms therefore can be exacerbated – headaches may be worse, or patients can be drowsy or the neurological deficits such as arm and leg weakness are exaggerated. For many years, corticosteroids (typically dexamethasone) have been used to reduce the swelling around brain tumours. Starting dexamethasone can be very effective in controlling symptoms caused by brain tumours such as glioblastoma (GBM), other malignant gliomas, metastatic brain tumours, low grade gliomas (astrocytomas, oligodendrogliomas) and benign tumours like meningiomas. Often this improvement occurs within hours. So dexamethasone is a very useful drug for short term control of symptoms.
We are all very familiar with the side effects of dexamethasone when its use is prolonged. It commonly causes weight gain, high blood sugar (making diabetes worse), muscle weakness, mood and behavioural changes, sleep disturbance, suppression of the immune system etc – the list goes on. So the use of dexamethasone should be limited to try to reduce or avoid some of these unpleasant side effects.
But there may be other reasons to avoid or limit the use of dexamethasone – because dexamethasone may adversely affect survival in people with malignant glioma (GBM, glioblastoma). A study published earlier this year (Pitter et al, Brain, 139: 1458-71) provided evidence that the use of dexamethasone during radiotherapy was associated with shorter survival in patients with GBM. These authors also used a mouse model to show that dexamethasone decreased the survival benefit of radiotherapy.
So what does this mean? It is generally accepted that the long term use of dexamethasone should be avoided if at all possible to avoid the unpleasant and sometime nasty effects of chronic use. The recent evidence though also strongly suggests that the use of dexamethasone should be minimised in the early stages of treatment. The following may be useful guidelines:
- The routine practice of maintaining patients on dexamethasone during radiotherapy in case they develop swelling is probably not justified and could be potentially harmful. Its use should be stopped if patients are asymptomatic and given only if a patient was to develop symptomatic oedema
- Steroids like dexamethasone are not needed in patients with asymptomatic brain tumours, including gliomas, GBM, and metastases
- Long term use should be minimised whenever possible
There is also an obvious need to have other medications that can help control the symptoms of cerebral swelling associated with brain tumours. Such agents are currently not available.
Prof David Walker is a neurosurgeon and spinal surgeon at BrizBrain & Spine. He has a special clinical interest in brain tumours and is actively involved in conducting research to help find a cure for this disease. Prof Walker is also the Managing Director of the Newro Foundation, a research organisation that conducts research into brain and spine conditions.