Breastfeeding and risk of childhood brain tumors : a report from the Childhood Cancer and Leukemia International Consortium

PURPOSE: Studies report mixed findings regarding the association of breastfeeding with childhood brain tumors (CBT), the leading causes of cancer-related mortality in young people. Our objective was to determine whether breastfeeding is associated with CBT incidence. METHODS: We pooled data on N = 2610 cases with CBT (including 697 cases with astrocytoma, 447 cases with medulloblastoma/primitive neuroectodermal tumor [PNET], 167 cases with ependymoma) and N = 8128 age- and sex-matched controls in the Childhood Cancer and Leukemia International Consortium. We computed unconditional logistic regression models to estimate the odds ratio (OR) and 95% confidence interval (CI) of CBT, astrocytoma, medulloblastoma/PNET, and ependymoma according to breastfeeding status, adjusting for study, sex, mode of delivery, birthweight, age at diagnosis/interview, maternal age at delivery, maternal educational attainment, and maternal race/ethnicity. We evaluated any breastfeeding versus none and breastfeeding ≥ 6 months versus none. We subsequently performed random effects meta-analysis to confirm our findings, identify potential sources of heterogeneity, and evaluate for outliers or influential studies. RESULTS: Breastfeeding was reported by 64.8% of control mothers and 64.5% of case mothers and was not associated with CBT (OR 1.04, 95% CI 0.94-1.15), astrocytoma (OR 1.01, 95% CI 0.87-1.17), medulloblastoma/PNET (OR 1.11, 95% CI 0.93-1.32), or ependymoma (OR 1.06, 95% CI 0.81-1.40). Results were similar when we restricted to breastfeeding ≥ 6 months and in meta-analyses. CONCLUSION: Our data suggest that breastfeeding does not protect against CBT.