Medulloblastoma

Medulloblastomas are primary malignant embryonal tumours of the central nervous system. They are the most common childhood central nervous system tumour, but are rare in the adult population. They arise infratentorially in the cerebellum or fourth ventricle and hence the most common presenting symptoms are those associated with raised intracranial pressure. Several histological subtypes have been described, although the classical and desmoplastic subtypes account for the majority. Recent advances in molecular biology and cytogenetics have led to an improved understanding of the genetic abnormalities and alterations in cell signalling pathways associated with medulloblastomas, including how these relate to patient outcome. The Modified Chang Staging System is still in use, but a number of other factors, including age, completeness of resection, histological subtype and genetic markers now contribute to treatment decisions and prognostication. Patients are currently classified as being either standard or high risk in order to stratify treatment. There has been an improvement in survival of all groups over the past 20 years. A multimodality approach is the cornerstone of treatment and recent trials have concentrated on ascertaining the most efficacious treatment combinations and timings for each patient group. Advances in surgical techniques have allowed a greater attainment of the two primary surgical goals: restoring normal cerebrospinal fluid (CSF) flow and maximal tumour resection. Radiotherapy to the craniospinal axis with a boost to the posterior fossa has been standard practice, but improvement in radiotherapy techniques and quality control has enabled optimisation of the trade-off between tumour control and normal tissue late toxicities. Combination chemotherapy is usually given adjuvantly, although it may be used to delay or avoid the use of radiotherapy in infants. In the future, the treatment of medulloblastoma will probably become increasingly individualised, based on patient-specific genetic features. Attention will be focussed not only on improving survival, but also on maintaining quality of life.