Season of birth and risk of brain tumors in adults

Background: Recent studies demonstrated an excess of winter births in children with brain tumors and in adults with various neurologic or psychiatric diseases relative to the general population. Objective: To investigate a possible association between month of birth and risk of brain tumors in adults using data from a large, hospital-based case-control study. Methods: Cases were patients with incident glioma ( n = 489) or meningioma ( n = 197) diagnosed at hospitals in Boston, MA, Phoenix, AZ, and Pittsburgh, PA. Controls ( n = 799) 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. Odds ratios (ORs) were calculated using multivariate unconditional logistic regression allowing for cyclic variation in risk with month of birth. Results: A relationship between month of birth and risk of adult glioma and meningioma was found, best described by a 12-month periodic function with peaks in February and January and troughs in August and July. The association between month of birth and risk of glioma differed significantly by handedness, with left-handed and ambidextrous subjects born during late fall through early spring being at particularly high risk of adult glioma as compared with those born at other times of the year. Conclusion: These findings suggest the importance of seasonally varying exposures during the pre- or postnatal period in the development of brain tumors in adults.