Medulloblastoma: symptoms, treatment and outlook

Medulloblastoma is an embryonal tumour, meaning it arises from immature cells. The Brain Tumour Charity describes it as the most common central nervous system embryonal tumour, accounting for 15 to 20 per cent of all childhood brain tumours. It develops in the posterior fossa, the part of the skull near the back of the head, most often in the cerebellum, which controls coordination and balance.

Cancer Research UK notes that doctors used to describe it as a primitive neuroectodermal tumour (PNET), but that term is no longer used. It adds that medulloblastoma can affect adults, although this is rare.

A diagnosis of any brain tumour in a child is frightening. It helps to know that the specialist teams that treat medulloblastoma are highly experienced, and that research in recent years has divided the tumour into subtypes so that treatment can be matched more closely to the biology of each case.

Cancer Research UK says a child might have symptoms for a few weeks or months before diagnosis and that many symptoms are general and non-specific, similar to less serious childhood illnesses. The Brain Tumour Charity highlights that headaches come on quickly and are often worse in the morning, and that the tumour can cause increased pressure in the skull.

• Headaches, particularly in the morning, which may ease after being sick.

• Feeling or being sick.

• Double vision, blurry vision or abnormal eye movements.

• Loss of balance and coordination, difficulty sitting or standing unsupported, or difficulty walking.

• Being more irritable, tired or having a loss of appetite or behaviour change.

• In babies, an increasing head size or swollen soft spot (fontanelle) picked up at routine checks.

Cancer Research UK advises taking your child to the GP if you are worried that your child has a symptom of a brain tumour. Most children with headaches, sickness or clumsiness do not have a brain tumour, but a combination of persistent morning headaches, vomiting, visual symptoms and balance problems should be taken seriously.

A child who has a sudden severe headache, repeated vomiting, drowsiness that is hard to rouse, a seizure or a rapid change in behaviour needs emergency assessment through 999 or A&E.

Cancer Research UK says the first tests a child might have are a CT scan and an MRI scan. They might also have a lumbar puncture, a test to check for cancer cells in the cerebrospinal fluid that surrounds the brain and spine. For some tests a child might need sedation or a general anaesthetic to help them lie still.

The tumour type cannot be confirmed without a sample. Cancer Research UK explains that the surgeon removes as much tumour as possible and takes a piece to look at under the microscope. The Brain Tumour Charity adds that genetic testing to determine the type of medulloblastoma is now available on the NHS and can also help the team to say whether a child could join clinical trials.

Cancer Research UK says that by appearance under the microscope there are 4 types: classical (about 8 out of 10 children), anaplastic or large cell, nodular or desmoplastic (most common in infants) and medulloblastoma with extensive nodularity. By looking at genes and proteins inside the cells there are 4 molecular subtypes.

The main treatments are surgery, radiotherapy and chemotherapy, and each child has their own plan. Cancer Research UK says surgery is usually the first treatment, aiming to remove as much tumour as possible. If fluid has built up in the brain (hydrocephalus), the surgeon can drain it with a ventriculostomy or a shunt, sometimes at the same time.

After surgery the child is assigned to a high risk or standard risk group based on factors such as age, whether the tumour has spread, how much was removed and the type. Cancer Research UK says all children under 3 are in the high risk group and that specialists usually avoid whole brain and spine radiotherapy in this age because of the higher risk of long-term side effects. Children aged 3 and over generally have chemotherapy and radiotherapy to the brain and spine, and some aged between 3 and 6 have chemotherapy only. Radiotherapy usually starts around 4 to 6 weeks after surgery and may last about 6 weeks.

Proton beam therapy, which Cancer Research UK says is usually used for children with standard risk medulloblastoma, is available in the UK at The Christie in Manchester and University College London Hospital. High risk disease may be treated with high-dose chemotherapy followed by an autologous stem cell transplant.

Cancer Research UK describes posterior fossa syndrome, a group of symptoms after surgery to the back of the brain, which affects around 25 to 30 out of 100 children. Symptoms can include difficulty talking or swallowing, poor balance, weakness on one side and mood changes. The symptoms usually develop from one day to a week after surgery and improve slowly over weeks or months, though they may not go away completely.

Radiotherapy and chemotherapy can have long-term effects on growth, hormones, hearing, learning and thinking. The Brain Tumour Charity gives a personal example of a young adult who takes growth hormone and vitamin D because of low bone density after radiotherapy. Children are followed in long-term follow-up clinics so that these effects can be anticipated and supported.

Outcome depends on the subtype, whether the tumour has spread and whether it could all be removed, so no single figure applies to every child. Cancer Research UK says the best person to discuss a child's outlook is their doctor, and the Brain Tumour Charity notes that the WNT subgroup is the best known of the four. Families should ask their team what the subtype and risk group mean for their child.

Practical and emotional support is available through the children's hospital team, a play specialist, clinical nurse specialists, school liaison and charities such as the Brain Tumour Charity and Cancer Research UK.

Childhood brain tumours in the UK are treated in NHS specialist children's cancer centres, with a multidisciplinary team including a paediatric neurosurgeon, oncologist, radiotherapist, specialist nurses and play specialists. Care is free at the point of use, and clinical trials are available through these centres.

Families occasionally seek a second opinion from another specialist centre. The treatment pathway and decisions are best taken with the principal treatment centre team.