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Bit of information sent to me which members may find interesting..
Treatment & Research
Medulloblastoma and its treatment
What is Medulloblastoma?
Medulloblastoma, sometimes called a primitive neuroectodermal tumour (PNET), is the most common type of malignant brain tumour. It occurs most commonly in childhood, usually under the age of 10 years. Approximately 80 patients are diagnosed each year in the UK. The cause is unknown in most cases. Medulloblastoma develops in the cerebellum, the part of the brain at the back of the head responsible for balance and co-ordination.
The most common symptoms of medulloblastoma are poor balance and coordination, headache, nausea and vomiting. These symptoms are not specific, and may be caused by other brain tumours and also less serious illnesses.
Medulloblastoma and PNET can spread through the cerebrospinal fluid (CSF) to other parts of the central nervous system. These tumours may block the flow of fluid through the brain leading to a condition called hydrocephalus with increased pressure inside the head.
How is suspected medulloblastoma investigated?
If a doctor, either a general practitioner (GP) or hospital accident and emergency doctor, suspects that an unwell child may have a serious underlying problem, a paediatrician or children’s specialist will be asked to assess the child. If a brain tumour is suspected, a brain scan, usually magnetic resonance imaging (MRI), will be performed. If this scan shows a brain tumour, the child will be transferred to a regional specialist paediatric neurosurgical centre for expert investigation and treatment.
Surgery will be undertaken – often just a single surgical procedure, although sometimes a series of operations will be needed. Surgery will relieve the increased fluid pressure within the head, remove as much of the tumour as is safely possible, and provide tumour tissue for a pathologist to analyse. Following surgery, a second scan is performed to find out how much of the tumour has been removed and to see whether the tumour has spread, and a CSF sample will be taken to see if there are still tumour cells present.
The results of all these tests will be discussed at a multi-disciplinary team meeting involving the paediatric specialists in neurosurgery, pathology, radiology (scan interpretation), and oncology (cancer treatment specialists in radiotherapy and chemotherapy). Patients can then be assigned to a risk group, which determines the intensity of further treatment, and the prospects for cure. Patients are designated as having standard risk medulloblastoma if they are over three years of age, have had a tumour which was confined to the cerebellum completely or almost completely removed, have a favourable type of medulloblastoma on pathology, and no evidence on MRI scan or CSF examination of spread of the disease. Patients are designated as having high risk medulloblastoma if there is evidence of spread, if there is significant disease left which cannot safely be removed, if the pathology report shows an unfavourable type of medulloblastoma, or if the child is less than three years of age.
How is medulloblastoma treated after surgery?
The treatment protocols for medulloblastoma have been developed and refined as a result of clinical trials carried out in the UK, Europe and America over recent decades, and taking into account progress which has been made in the understanding of the scientific basis of medulloblastoma, advances in scanning, and improvements in chemotherapy and radiotherapy techniques.
These trials have shown that the best outcomes are achieved with a combination of radiotherapy (X-ray treatment) and chemotherapy (drug treatment). In children over three years of age, radiotherapy is an essential component of treatment. The whole brain and spine are treated with radiotherapy, because of the tendency for medulloblastoma to spread through the CSF to parts of the nervous system beyond the back of the brain where the tumour initially started to grow. Ideally radiotherapy should be commenced within four weeks after surgery but this depends on how well the child has recovered from the operation. Up to one in three children with medulloblastoma may develop a condition known as posterior fossa syndrome or cerebellar mutism. This is a condition of unknown cause that varies in severity but is best viewed as an acquired brain injury that usually recovers over time. Many CCLG units prefer to delay radiotherapy under these circumstances to allow the brain to recover and bring forwards chemotherapy to ensure there is no delay in treatment.
All treatments, both chemotherapy and radiotherapy, are associated with possible long term side effects. Research has shown that more recent treatment protocols, which are associated with a dose reduction in standard risk medulloblastoma, are associated with fewer side effects. Younger children tend to experience worse long term side effects, which is why radiotherapy is not always given to the whole brain and spine in the youngest children.
What is proton beam radiotherapy?
Proton beam radiotherapy is a relatively new type of radiotherapy. At the moment, there are no high-energy proton beam radiotherapy facilities in the United Kingdom, but two centres are currently planned - one in London, the other in Manchester - which will start to treat patients in 2018. Until these new English centres are opened, the NHS will continue to pay for proton beam radiotherapy for children (and some adults) who will benefit from this new treatment, in foreign centres, principally in the USA. Patients are carefully selected so that those who may be better treated by protons will have their treatment, travel and living expenses funded.
Is proton beam radiotherapy more effective than standard radiotherapy?
No. Proton beam radiotherapy has exactly the same effect on irradiated cancers and healthy normal tissues as conventional (X-ray or photon) radiotherapy. This means that proton beam radiotherapy does not offer a greater prospect of cure than conventional radiotherapy.
Does proton beam radiotherapy reduce side effects in children with brain tumours?
For some, probably. The advantage of protons is that it is possible to reduce the radiation dose to healthy tissues outside the area which needs treatment. This is especially valuable with small tumours located centrally in the brain, where only local treatment is needed. In such cases proton beam radiotherapy can theoretically reduce this, resulting in fewer long term side effects. The benefits of proton beam radiotherapy are not universal, but are limited to certain patients only.
Does proton beam radiotherapy offer advantages for children with medulloblastoma?
This is not known. Unfortunately, even in standard risk medulloblastoma, it is necessary to treat the whole brain and spine, as all this area is at risk of tumour recurrence if it is not adequately treated. Using proton beam radiotherapy would not avoid the most serious long-term side effects of treatment, such as growth hormone insufficency or effects on how survivors perform academically.
It may be possible to reduce the radiation dose to certain, key areas of the brain by using protons. Theoretically, this may reduce some of the side effects, particularly in relation to future brain development, but at the present time, there is not sufficient evidence to say if this is, or is not the case.
The risk of causing certain second cancers, such as thyroid cancer may be less, but the risk of this is very small indeed already. The risk of causing other tumours, such as meningioma is unlikely to be different.
Does proton beam radiotherapy have any disadvantages for children with medulloblastoma?
Yes. The most important consideration here is the time to begin treatment. It is clear that a prolonged delay in starting treatment is associated with an increased risk of the tumour coming back. Beginning radiotherapy early is an important factor in the best treatment of medulloblastoma.
Travelling abroad when a child is very ill is itself potentially dangerous, especially after often complex surgical operations. Finally, living in another country for an extended period (8-10 weeks) during treatment can cause great pressure on children and their families. Until protons are available in the UK, it is likely that treatment with conventional treatment will be deliverable sooner, and with less disturbance to families.
Medulloblastoma is therefore not recognised as an indication for proton beam radiotherapy. Even in America and those European countries where proton beam radiotherapy is more readily available, the majority of children will receive conventional radiotherapy.
What are the prospects for cure of medulloblastoma?
Approximately four out of five standard risk medulloblastoma patients will be cured, which means the tumour will never come back. While most children will experience long-term side effects of treatment, many survivors will lead relatively normal lives, continuing their education and having an independent adult life. Unfortunately those with high-risk disease require more intensive treatment, and the prospects for cure are less good.
The Children’s Cancer and Leukaemia Group
The Children’s Cancer and Leukaemia Group (CCLG) is a charity which works for the benefit of children and young people diagnosed with leukaemia and cancer, and their families, through the provision of information and the funding, support and promotion of research.
As the professional association for those involved in the treatment and care of children and younger teenagers with cancer and leukaemia, we work to ensure that all children receive the best possible treatment, a greater chance of survival and a better life after treatment. We guide and share best practice, and advocate excellence and equal access to cancer care. |
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Author: Cliff
26-11-2019 02:26:32
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