Brain tumours in children

Tumours of the central nervous system are the commonest solid tumours in paediatrics. Among childhood malignancies, they are second in incidence only to leukaemia. Advances in diagnostic procedures and treatment modalities have improved the prognosis but brain tumours still constitute a major cause of death in childhood. In addition, many of the survivors are left with variable degrees of disabilities, which implies suffering for the individual and a burden for the family and society. A close follow-up of tumour classification, incidence and the results of treatment in passed decades is integral to future progress. In this issue, Lannering et al. (1) present information about the incidence of brain tumours in children diagnosed in Sweden during 1984–2005 and data on survival rates. Earlier international studies indicated a high incidence in Sweden but also good results of treatment like the other Nordic countries. Doubts had been raised, however, about the validity of the data in the Swedish Cancer Registry in this context because of a large proportion of ‘unspecified’ cases. The Swedish Childhood Cancer Registry is operative since the 1980s thanks to the devoted work of paediatric oncology pioneers among whom are authors of this study. The registry contains more detailed information about diagnostic criteria, treatment protocols and follow-up provided by all the Paediatric Oncology Centres in Sweden. Another strength is that a detailed subdivision of tumours was applied based on the latest International Classification of Childhood Cancer (ICCC-3). The great majority of patients could be assigned to one of the categories leaving only 2.5% unspecified cases, which makes the data more solid. The new data confirm a mean annual incidence of brain tumours close to 4.0 ⁄ 100 000 children below 15 years. This figure is in fair agreement with the other Nordic countries and more recent data from the USA and the UK, although differences in individual tumours exist. Some countries still report a lower incidence which may partly be explained by under-reporting of more benign tumours. An increasing incidence of brain tumours among children in Sweden has been suggested by a few papers that include data from the 1960s and 1970s (2,3). Data from Denmark and other European countries also suggest a rising incidence (4). Whether this is a true increase or explained by a heightened awareness during later years and the introduction of CT and MRI in clinical practice is still uncertain. Anyway, it is reassuring that Lannering et al. did not find an increasing incidence in Sweden over the study period but rather a negative trend during the last 5 years. In earlier collaborative European studies, the survival rate after treatment for brain tumours was found to be higher in the Nordic countries than in other countries and has been nominated the gold standard of treatment. The total survival rate according to Lannering et al. (1) was over 70% and is impressive compared with the clinical experiences only a few decades ago. It illustrates the painstaking collaborative efforts to improve diagnostic measures, treatment and not least registration and follow-up. Brain tumours are, however, a very heterogeneous group of diseases and a meaningful comparison between treatment results can obviously be accomplished only when the material is broken down in different tumour types. This study confirms the good prognosis for low-grade astrocytomas, which can often be cured by surgery alone, and the intermediate results in ependymoma and medulloblastoma. For malignant brainstem gliomas, the outlook is still gloomy and for Invited commentary for Lannering B et al. Classification, Incidence and Survival Analyses of Children with CNS Tumors diagnosed in Sweden 1984–2005. Acta Pædiatrica ISSN 0803–5253