Allergy and brain tumors in the INTERPHONE study: pooled results from Australia, Canada, France, Israel, and New Zealand.

PURPOSE: A history of allergy has been inversely associated with several types of cancer although the evidence is not entirely consistent. We examined the association between allergy history and risk of glioma, meningioma, acoustic neuroma, and parotid gland tumors using data on a large number of cases and controls from five INTERPHONE study countries (Australia, Canada, France, Israel, New Zealand), to better understand potential sources of bias in brain tumor case-control studies and to examine associations between allergy and tumor sites where few studies exist.
METHODS: A total of 793 glioma, 832 meningioma, 394 acoustic neuroma, and 84 parotid gland tumor cases were analyzed with 2,520 controls recruited during 2000-2004. Conditional logistic regression models were used to obtain odds ratios (ORs) and 95 % confidence intervals (CIs) for associations between self-reported allergy and tumor risk.
RESULTS: A significant inverse association was observed between a history of any allergy and glioma (OR = 0.73, 95 % CI 0.60-0.88), meningioma (OR = 0.77, 95 % CI 0.63-0.93), and acoustic neuroma (OR = 0.64, 95 % CI 0.49-0.83). Inverse associations were also observed with specific allergic conditions. However, inverse associations with asthma and hay fever strengthened with increasing age of allergy onset and weakened with longer time since onset. No overall association was observed for parotid gland tumors (OR = 1.21, 95 % CI 0.73-2.02).
CONCLUSIONS: While allergy history might influence glioma, meningioma, and acoustic neuroma risk, the observed associations could be due to information or selection bias or reverse causality.