Childhood medulloblastoma in Denmark 1960-1984. A population-based retrospective study.

Medulloblastoma is a common paediatric brain tumour, located in the cerebellum and in the IV ventricle, surpassed in frequency only by astrocytomas. 180 children below the age of 15 with a medulloblastoma of the posterior fossa were treated in Denmark in the 25-year period from 1960 to 1984 and followed up until the end of 1996, or until death. During the 25 years they accounted for 20% of all intracranial tumours in children in Denmark. All tumours were histologically verified. The mean annual incidence was 6.4x10(-6), decreasing slightly with a factor of 0.12x10(-6) per year. The male/female ratio was 2.1 - twice that of the background population of children (1.05). The 5-year survival rate following diagnosis, surgery and radiotherapy was 23%, and the 25-year survival rate was 16%. The 5-year survival rate was 8% in the first 5-year period of 1960-1964, increasing to 36% in the last period 1980-1984. Presumably the increase in survival depends on many factors, e.g. improved diagnostic methods and neuroanaesthesia, better operative technique (microscope), improvements in radiotherapy and the introduction of chemotherapy. The best predictive factors of a good prognosis were preoperative CSF shunting, radical tumour removal and complete radiotherapy, i.e. irradiation of the brain, tumour bed and spinal cord. The survival rate in the last five-year period was seven times higher than the survival rate found in a comparable Danish study from the years 1935-1959. Most of the children followed Collins law of risk index. The results of treatment in children with medulloblastoma remain unsatisfactory. Accordingly, participation in international prospective studies of multimodal treatment should be encouraged, possibly using chemotherapy prior to surgery.