Summary
Medulloblastoma is the most common malignant brain tumour occurring in children, adolescents and young adults. It derives from the neuroectoderm and develops in the cerebellum (80% occur in the vermis and 20% occur in the hemispheres). It accounts for 10 to 20% of brain tumours and for 30% of tumours located in the posterior fossa. Incidence is around 5 to 10/million children between 0 and 14 years of age per year. The frequency peak is at around 5 years of age. The cause of the disease is not known in most of the cases but genetic predisposition is seen in around 10% of cases, mainly in association with Gorlin syndrome. Other genetic syndromes that have been associated with medulloblastoma are: neurofibromatosis type 1 and neurofibromatosis type 2, Rubinstein-Taybi syndrome, Fanconi anemia, Nijmegen breakage syndrome, Turcot syndrome with APC mutations and Li-Fraumeni syndrome. Medulloblastomas have a strong tendency to disseminate within the central nervous system (CNS), particularly in the cerebrospinal fluid and meninges, but metastases have also been found outside the CNS (for example, in the bone marrow). Classically, patients are treated by surgical excision of the primary tumour with local (posterior fossa boost) and extended radiation therapy over the entire neuraxis. Adjuvant chemotherapy has been proved to be useful whatever the stage of the disease. The disease and its treatment lead to long term sequelae, e.g. endocrine and intellectual disorders, especially when children are treated at a young age or when surgery has been complicated. Neuropsychological testing assesses the damage and helps to establish the type of education, rehabilitation, and measures for reinsertion required. New chemotherapeutic treatments are now being evaluated to minimize treatment-related toxicity, e.g. by avoiding radiation therapy in young children. Current protocols yield disease-free survival rates of 50 to 70%, depending on the quality of excision and staging. Patient management requires a pluridisciplinary team with expertise in the field of paediatric cancer. Patients should be treated within prospective therapeutic trials where early rehabilitation is part of the treatment plan. *Author: Dr. J. Grill (February 2005)*.
