Background There are few established determinants of brain tumour. We assessed among adults the risk of brain tumour in relation to metabolic syndrome factors.

Methods 580 000 subjects from Sweden, Austria, and Norway were followed for a median of 10 years (Me-Can). Brain tumour information was obtained from national cancer registries. The factors of metabolic syndrome, body mass index, blood pressure, and blood levels of glucose, cholesterol, and triglycerides, were analysed in quintiles and for transformed z-scores (mean of 0 and SD of 1). Cox proportional hazards regression models were applied, stratified by cohort and corrected for measurement error.

Results In total 1312 primary brain tumours were diagnosed during follow-up, predominantly high-grade glioma (n=436) and meningioma (n=348). For meningioma, the HR was increased for systolic blood pressure (HR=1.27 per unit SD, 95% CI 1.03 to 1.57), for diastolic blood pressure (HR=1.29, 95% CI 1.04 to 1.58), and for the combined metabolic syndrome score (HR=1.31, 95% CI 1.11 to 1.54). For high-grade glioma the risk was increased for diastolic blood pressure (HR=1.23, 95% CI 1.01 to 1.50) and triglycerides (HR=1.35, 95% CI 1.05 to 1.72). For both meningioma and high-grade glioma, the risk was more than doubled in the fifth quintiles of diastolic blood pressure compared to the first quintile. For systolic blood pressure the meningioma risk was even larger.

Conclusion Increased blood pressure was related to risk of brain tumour, particularly of meningiomas.