To explore a possible influence of the immune system in the development of brain tumors, we evaluated the relationship between history of allergies and autoimmune diseases and risk of brain tumors within a large, hospital-based casecontrol study. Cases (n ؍ 782) were patients recently diagnosed with glioma (n ؍ 489), meningioma (n ؍ 197) or acoustic neuroma (n ؍ 96) at hospitals in Boston, Phoenix and Pittsburgh (USA). Controls (n )997؍ were patients hospitalized for a variety of nonmalignant conditions and frequency-matched to cases by hospital, age, sex, race/ethnicity and distance of residence from hospital. Research nurses collected data by personal interview of patients. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression. There was a significant inverse association between glioma and history of any allergies ; glioma; meningioma; neuroma, acoustic; adult; risk factors; hypersensitivity; autoimmune diseases Despite much study, the etiology of brain tumors remains largely unknown. Several familial cancer syndromes, such as neurofibromatosis, tuberous sclerosis and Li-Fraumeni syndrome, are associated with increased risk but these account for less than 5% of all cases. 1-3 Only 1 environmental risk factor, ionizing radiation, is well established. 1 In the continued search for clues to the etiology of brain tumors, it is important to consider factors that might protect against brain tumors as well as factors that might cause them. Recent studies raise the question of whether persons with a hyperstimulated immune system might be at reduced risk of brain cancer.Results of case-control studies published during the past decade 4 -9 suggest an approximately 40% lower risk of glioma, but not meningioma, associated with a history of allergic diseases, including asthma, eczema and others. Evidence from prospective studies is very limited, largely because brain cancer is an uncommon disease. 10 Diabetes also has been negatively associated with risk of glioma in some studies 5,11 but not in others. 7,8,12,13 Several cohort studies of patients with rheumatoid arthritis, 14 pernicious anemia 15 and multiple sclerosis 16,17 failed to demonstrate a decreased risk of brain tumors. The findings regarding infections and brain tumors, while suggestive of a negative association, are mixed. 5,7,8,18,19 Although available data on a broad range of specific medical disorders are inconsistent, immunologically mediated conditions warrant further investigation as factors that might interfere with brain tumor development.Here, we report the associations between history of allergies and autoimmune diseases and risk of glioma, meningioma and acoustic neuroma based on data from a large, case-control study conducted at 3 hospitals in the United States. Associations with prior infections will be addressed in a separate report.
MATERIAL AND METHODS
Study population and settingDetails of our study were described previously. 20 Of the potentially eligible cases invited to par...