Birth weight and risk of neuroblastoma: a meta-analysis.

BACKGROUND Neuroblastoma is the most common solid tumour in infancy but its aetiology is largely unknown. Prenatal factors might play a key role in its pathogenesis. Previous studies investigated whether birth weight is associated with risk of neuroblastoma, with conflictive results. We conducted a meta-analysis to quantitatively summarize the published evidence. METHODS Results from 10 case-control studies and one cohort study (1966 to December 2008) were included, involving a total of 3004 children with neuroblastoma. We constructed random-effects and fixed-effects models, performed 'pool-first' analyses, assessed heterogeneity and publication bias and performed sensitivity and influence analyses. RESULTS High birth weight (>4000 g) was associated with increased risk of neuroblastoma [odds ratio (OR) 1.19; 95% confidence interval (CI) 1.04-1.36]. Results for high birth weight were highly homogenous (I(2) = 0%). Low birth weight (<2500 g) was also related to increased risk of neuroblastoma (OR 1.24; 95% CI 1.0-1.55), but results were more heterogeneous (I(2 )= 30%). No evidence for particularly influential studies or for publication bias was found. However, sensitivity analysis indicated the presence of bias in studies on the association with low birth weight. Above 2500 g each 1000-g increase in birth weight was associated with a 13% (95% CI 3-25) increase in risk of neuroblastoma. CONCLUSIONS This meta-analysis shows that high birth weight is highly reproducibly associated with increased risk of neuroblastoma. The association with low birth weight was found to be less robust and deserves further studies.