Medulloblastoma

Tumour Group:
Pediatric Brain Tumours
WHO Grade:
Grade IV
Prevalence/Incidence:
Medulloblastoma is relatively rare and accounts for less than 2% of all primary brain tumours and 18% of all pediatric brain tumours. Medulloblastoma occurs more often in men than in women.
Typical Age Range:
More than 70% of all pediatric medulloblastomas are diagnosed in children under age 10; very few occur in children up to age one. Medulloblastoma in adults is far less common, but does occur. About one-third of all medulloblastomas diagnosed in the United States are found in adults between the ages of 20-44. The incidence in adults sharply decreases in frequency after age 45, with very few older adults having this tumour.

Tumour Characteristics

Medulloblastoma is a fast-growing, high-grade brain tumour. Like many tumour types, the exact cause of medulloblastoma is not known. However, scientists are making significant strides in understanding its biology.

Changes have been identified in genes and chromosomes (the cell’s DNA blueprints) that may play a role in the development of this tumour. There are also a few rare, genetic health syndromes that are associated with increased risk for developing this tumour. These include Gorlin syndrome and Turcot syndrome.

Different subtypes of medulloblastoma tumours have recently been identified and described using “molecular classification.” Each subtype has different characteristics and may:

  • Be more likely to occur in a specific patient age range
  • Have different pathological, genetic and molecular biology characteristics
  • Have different clinical outcomes (some subtypes have a much better prognosis than others)

This classification was outlined in a manuscript produced as a result of a consensus conference held by experts in Boston, MA in 2010. The four main subtypes of medulloblastoma are:

  1. Wnt
  2. Shh (Sonic Hedgehog subgroup)
  3. Group 3 tumours
  4. Group 4 tumours

Research through the Pediatric Brain Cancer Impact Grant has shown that there are twelve subtypes of medulloblastoma.

Symptoms

Common symptoms include, but are not necessarily limited to:

  • Behavioural or personality changes
  • Double vision
  • Headaches (which are worse first thing in the morning)
  • Lack of coordination
  • Lethargy or sleepiness
  • Vomiting

Treatment/Standard of Care

The management of medulloblastoma involves a multidisciplinary team:

  • Surgery is the most important first-line treatment and involves removing as much of the tumour as possible.
  • Sometimes the CSF pathways do not re-establish themselves after surgery and then a shunt may be necessary to treat the raised intracranial pressure (hydrocephalus).
  • Chemotherapy is usually an important part of the treatment plan. In very young children aged 3 years or less, it is standard to treat children with medulloblastoma using chemotherapy alone as radiation therapy can be associated with significant long-term health problems (late effects).
  • Radiation therapy is used for older children and involves treatment of the brain and spine followed by a “boost” of extra radiation therapy to the area where the tumour started in the posterior fossa.

Prognosis

A prognosis is an estimate of the likely progress of a disease after a diagnosis, based on an average patient group. Since every person is different, please take time to talk with your health care team about how this information applies to you.

By clicking on 'expand', a statistic on the prognosis for Medulloblastoma will be shown.