Circannual distribution of glioblastoma and anaplastic astrocytoma diagnoses in men and women

Background: circannual variations of incidence may influence human tumors. For example, seasonal distribution of breast cancers suggests an influence of circannual hormonal rhythms. Periodicity of brain tumors has not yet been investigated. The aim of this study was to assess the seasonal variation in glioblastomas and anaplastic astrocytomas. Methods: a large dataset of high-grade gliomas (n = 697) was evaluated with the month of diagnosis as key criterion for time series and seasonal analysis. Circannual and ultra-annual cosinor models were calculated. Results: women suffering from glioblastoma show a peak incidence in fall. No suitable circannual or ultra-annual cosinor model months could be fitted to the data. In women with anaplastic astrocytoma, a peak incidence was detected in summer and fall with a nadir in spring. Here, a significant cosinor model with a period of 8.5 months could be calculated. Conclusion: our data strongly suggest seasonality of diagnosis of high-grade gliomas in women. As gliomas express hormonal receptors, an underlying endocrinal or cell proliferation rhythms may be a possible explanation.