Maternal and perinatal risk factors for childhood brain tumors (Sweden)

Abstract

Childhood brain tumors (CBT) include a diversity of rare neoplasms of largely unknown etiology. To assess possible maternal and perinatal risk factors for CBT according to subtype, we carried out a nested (within Swedish birth-cohorts, 1973-89) case-control study, utilizing data from the nationwide Birth Registry. We ascertained incident brain tumor cases through linkage of the nationwide Birth and Cancer Registries and randomly selected five living controls from the former, matching each case on gender and birthdate. There were 570 CBT cases, including 205 low grade astrocytomas, 58 high grade astrocytomas, 93 medulloblastomas, 54 ependymomas, and 160 'others.' Risks for all brain tumors combined were elevated in relation to: (i) three maternal exposures-oral contraceptives prior to conception (odds ratios [OR] = 1.6, 95 percent confidence interval [CI] = 1.0-2.8), use of narcotics (OR = 1.3, CI = 1.0-1.6), or penthrane (OR = 1.5, CI = 1.1-2.0) during delivery); (ii) characteristics of neonatal distress (a combined variable including low one-minute Apgar score, asphyxia [OR = 1.5, CI = 1.1-2.0]) or treatments for neonatal distress (use of supplemental oxygen, ventilated on mask, use of incubator, scalp vein infusion, feeding with a jejunal tube [OR = 1.6, CI = 0.9-2.6]); and (iii) neonatal infections (OR = 2.4, CI = 1.5-4.0). Higher subtype-specific risks, observed for a few risk factors, did not differ significantly from the risk estimates for all subtypes combined for the corresponding risk factors. Childhood brain tumors were not associated significantly with other maternal reproductive, lifestyle, or disease factors; perinatal pain, anesthetic medications, birth-related complications; or with birthweight, birth defects, or early neonatal diseases. These findings suggest several new leads, but only weak evidence of brain tumor subtype-specific differences.

Childhood solid tumours in relation to infections in the community in Cumbria during pregnancy and around the time of birth

“…As many comparisons were made, this may be a consequence of multiple hypothesis testing. However, several factors support a genuine association: the effect was more marked in younger children and was consistent across several types of infection, and other studies have reported evidence of an infective aetiology of these tumours (Linet et al, 1996;Linos et al, 1998;Fear et al, 2001;McNally et al, 2002).…”

“…No account could be taken of urban and rural areas within county districts, although they probably have different patterns of infection; we assumed that during pregnancy mothers were living in the area where their children were born, which is unlikely to be true for all; deaths from respiratory infections and influenza will reflect the standard of clinical care as well as the prevalence of infection in the community. In contrast to case -control studies (Bithell et al, 1973;Linet et al, 1996;McKinney et al, 1999;Fear et al, 2001) and some cohort studies (Adelstein and Donovan, 1972;Fedrick and Alberman, 1972), we did not have measures of individual exposure.…”

“…Some epidemiological studies have provided tentative direct evidence of the involvement of maternal viral infections in childhood brain tumours (Linos et al, 1998;Fear et al, 2001), while others have not found such an association (Bunin et al, 1994;McKinney et al, 1999). Similarly, there is conflicting evidence about the role of neonatal infections (Linet et al, 1996;McKinney et al, 1999). The apparently contrasting findings of these studies may be due to the differences in the infections and types of tumours studied.…”

“…However, subsequent studies did not confirm this association and interest in this area waned (Leck and Steward, 1972;Curnen et al, 1974;Randolph and Heath, 1974). However, recent epidemiological studies have suggested that exposure to infections before or around birth may be associated with the risk of solid tumours, in particular brain tumours, in children (Linet et al, 1996;Linos et al, 1998;McKinney et al, 1999;Fear et al, 2001;McNally et al, 2002). In addition, it has been suggested that JC virus has a role in the aetiology of brain tumours (Khalili, 2001).…”

Childhood cancer incidence in a cohort of twin babies

“…Table 3 shows the results of the five previous prospective studies of cancer occurrence in twins (and our own). Of six heavily overlapping studies of childhood cancer from Sweden, (Forsberg and Källen, 1990;Zack et al, 1991;Cnattingius et al, 1995;Linet et al, 1996;Mogren et al, 1999;Rodvall et al, 1992), only one (Rodvall et al, 1992) reported a numerical risk for all childhood cancers in twins, that could therefore be included in a pooled analysis. Only one retrospective case-control study was identified (Savitz and Ananth, 1994) reporting a non-significantly increased odds ratio 1.5 (0.4-5.0).…”