SEARCH international case-control study of childhood brain tumours: role of index pregnancy and birth, and mother's reproductive history

A series of co-ordinated population-based case-control studies of childhood brain rumours (CBT) was undertaken under the auspices of the Surveillance of Environmental Aspects Related to Cancer in Humans (SEARCH) programme of the International Agency for Research on Cancer (IARC) to evaluate, inter a lia, the risk in relation to characteristics of the index pregnancy and bir th, and maternal reproductive history. Subjects comprised 1218 cases aged 0 -19 years and 2223 controls. Risk estimates were calculated by unconditiona l logistic regression, adjusted for age, sex, centre and mother's years of schooling, for all lyres of CBT combined as well as for four groups defined by histopathology (astroglial tumours, primitive neuroectodermal rumours o f the brain, 'other glial' tumours and 'other histological types') and for five age groups (0-1, 0-4, 5-9, 10-14, 15-19 years). Use of anaesthetic 'ga s' was associated with an increased risk of CBT (OR=1.5, 95% CI [1.1, 2.0]) , apparent in children aged 0-4 years (OR=2.4, 95% CI [1.4, 4.1]) and for a stroglial tumours (OR = 1.6, 95% CI [1.1, 2.2]) with non-significantly incr eased relative risks for each of the other histological groups. However, no t all centre-specific relative risks were elevated. No other aspect of the index pregnancy, delivery and early neonatal period or of the mother's prev ious reproductive history was associated with risk for CBT.