Central nervous system tumours in children: Epidemiology and risk factors

Abstract

In children, a variety of distinct tumour types arise in the central nervous system (CNS) but they are frequently considered by epidemiologists as a single entity. CNS tumours are the second most common childhood malignancy and occur more frequently in developed countries than developing nations. Approximately 50% of paediatric CNS tumours are gliomas, with astrocytomas of the piloctyic type predominating. Distributions of subtypes by age show that primitive neuroectodermal tumours (PNET) and ependymomas mainly occur in children less than 10 years. There is an ongoing debate with regard to the apparent increases in incidence over recent decades, which, it has been suggested, are accounted for by improved diagnostic technologies implemented in the mid 1980s. CNS tumours differ between children and adults with respect to the proportion of all cancers (20% in children, less than 2% in adults), their cellular origins, classification scheme, the proportions of pathological subtypes, and anatomic site. The causes of childhood CNS tumours are largely unknown; and although an estimated 5% or more may be explained by genetic predisposition, investigations of environmental aetiology have not been fruitful. Whilst high dose ionising radiation is an established risk factor for this group of tumours, reported associations with dietary N-nitroso compounds have not been consistent. Exposure to ELF EMF, at any level, has not been associated with childhood CNS tumours, but the current evidence base is inadequate for complete evaluation. The rarity of childhood CNS tumours necessitates careful attention being paid to the design of future aetiological studies.

Infectious exposure in the first year of life and risk of central nervous system tumors in children: analysis of day care, social contact, and overcrowding

“…Conversely PNETs form a major group in children, but are rare in adults [39]. It is therefore likely that specific childhood and adult tumors have different aetiologies [40].…”

Asthma and risk of brain cancer in children

“…Current thinking suggests that brain tumors develop in children as a consequence of accumulated genetic alterations that permit cells to evade normal regulatory mechanisms and destruction by the immune system. These alterations in the germ line may be inherited, but neurocarcinogens, agents of a chemical, biological, or physical nature, that damage DNA can lead to somatic mutations [2]. The causes of CNS cancers are largely unknown, but causes are likely to be both genetic and environmental.…”

“…In this age group, astrocytoma accounts for the 40% of tumors, followed by primitive neuroectodermal tumors (PNET) (22%), other gliomas (12%), other specified intracranial neoplasms (12%), and ependymoma (10%) [1]. Risk factors for CNS studied in adults may be different in children [2]. Current thinking suggests that brain tumors develop in children as a consequence of accumulated genetic alterations that permit cells to evade normal regulatory mechanisms and destruction by the immune system.…”

Effect of extremely low frequency magnetic field on antioxidant activity in plasma and red blood cells in spot welders

“…Although the increased risk of cancer or pregnancy outcome has not been conWrmed in epidemiological studies (Kheifets and Shimkhada 2005;McKinney 2005;Lagorio and Salvan 2001), recently the experimental and cellular studies have demonstrated that ELF-MF exposure can lead to chromosomal damage and gene destruction resulting in induction or promotion of cancer (Di Carlo et al 2002;Winker et al 2005;Scassellati et al 2004;Ivancsits et al 2002;Chen et al 2000). Some investigators suggest that DNA damage mechanism is an oxidative stress induced by ELF-MF (Strasak et al 2002, Yokus et al 2005Wolf et al 2005).…”