Role of medical history in brain tumour development. Results from the international adult brain tumour study

In an international population based case-control study carried out in 8 ce ntres in 6 countries, we investigated the role of specific medical conditio ns in the aetiology of brain tumours in adults. Recruited were 1,178 glioma and 331 meningioma cases and 2,493 age- and gender-matched population cont rols. Only medical conditions occurring at least 2 years before brain tumou r diagnosis were considered. Relative risks (RRs) and 95% confidence interv als (Cls) were estimated using a conditional logistic regression model. Het erogeneity between centres was tested. No association between meningioma an d previous medical conditions was observed. For glioma, there was an increa sed risk associated with epilepsy (RR = 6.55, 95% CI 3.40-12.63), but this was considerably weaker for epilepsy of more than 20 years duration. The ri sk remained elevated after adjustment for use of anti-epileptic drugs. Ther e was a statistically significant inverse association between glioma and al l allergic diseases combined (RR = 0.59, 95% CI 0.49-0.71); this was also o bserved for specific allergic conditions, namely, asthma and eczema. Subjec ts who reported a history of infectious diseases (e.g., colds, flu) showed a 30% reduction in risk (RR 0.72, 95% CI 0.61-0.85). The decreased risks fo r glioma in subjects reporting a history of allergic conditions or infectio us diseases may indicate an influence of immunological factors on the devel opment of glioma. The association between glioma and epilepsy has to be int erpreted cautiously and needs further investigation. (C) 1999 Wiley-Liss, I nc.