title: Body mass index, physical activity, and risk of adult meningioma and glioma: A meta-analysis.
abstract: OBJECTIVE
  Whether adiposity and lack of physical activity affect the risk for developing meningioma and glioma is poorly understood. Our objective was to characterize these associations in detail.
  
  
  METHODS
  We conducted a systematic review and meta-analysis of adiposity and physical activity in relation to meningioma and glioma using cohort and case-control studies published through February 2015. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.
  
  
  RESULTS
  We identified 12 eligible studies of body mass index (BMI) and 6 studies of physical activity, comprising up to 2,982 meningioma cases and 3,057 glioma cases. Using normal weight as the reference group, overweight (summary relative risk [RR] = 1.21, 95% confidence interval [CI] = 1.01-1.43) and obesity (RR = 1.54, 95% CI = 1.32-1.79) were associated with increased risk of meningioma. In contrast, overweight (RR = 1.06, 95% CI = 0.94-1.20) and obesity (RR = 1.11, 95% CI = 0.98-1.27) were unrelated to glioma. Similarly, dose-response meta-analyses revealed a statistically significant positive association of BMI with meningioma, but not glioma. High vs low physical activity levels showed a modest inverse relation to meningioma (RR = 0.73, 95% CI = 0.61-0.88) and a weak inverse association with glioma (RR = 0.86, 95% CI = 0.76-0.97). Relations persisted when the data were restricted to prospective studies, except for the association between physical activity and glioma, which was rendered statistically nonsignificant (RR = 0.91, 95% CI = 0.77-1.07).
  
  
  CONCLUSIONS
  Adiposity is related to enhanced risk for meningioma but is unassociated with risk for glioma. Based on a limited body of evidence, physical activity is related to decreased risk of meningioma but shows little association with risk of glioma.
authors.affiliation: From the Department of Epidemiology and Preventive Medicine, University of Regensburg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Niedermaier
authors.affiliation: From the Department of Epidemiology and Preventive Medicine, University of Regensburg, Germany. gundula.behrens@klinik.uni-regensburg.de.
authors.forename: Gundula
authors.initials: G
authors.lastname: Behrens
authors.affiliation: From the Department of Epidemiology and Preventive Medicine, University of Regensburg, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Schmid
authors.affiliation: From the Department of Epidemiology and Preventive Medicine, University of Regensburg, Germany.
authors.forename: Inga
authors.initials: I
authors.lastname: Schlecht
authors.affiliation: From the Department of Epidemiology and Preventive Medicine, University of Regensburg, Germany.
authors.forename: Beate
authors.initials: B
authors.lastname: Fischer
authors.affiliation: From the Department of Epidemiology and Preventive Medicine, University of Regensburg, Germany.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Leitzmann
mesh_terms: D015992:Body Mass Index; D001932:Brain Neoplasms / Q000150:complications / Q000503:physiopathology*; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology; D005910:Glioma / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008577:Meningeal Neoplasms / Q000150:complications / Q000503:physiopathology*; D008579:Meningioma / Q000150:complications / Q000503:physiopathology*; D009043:Motor Activity / Q000502:physiology*; D009765:Obesity / Q000150:complications; D011446:Prospective Studies; D012307:Risk Factors