Body mass index and risk of brain tumors: a systematic review and dose-response meta-analysis.

BACKGROUND/OBJECTIVES: Data regarding the relationships between body mass index (BMI) and brain tumors are inconsistent, especially for the commonly seen gliomas and meningiomas. Therefore, we conducted a dose-response meta-analysis to unravel the issue.

SUBJECTS/METHODS: Cochrane Library, PubMed and Embase were searched for pertinent case-control and cohort studies updated to November 2014. Dose-response and quantitative analysis were conducted with random-effect model.

RESULTS

Sixteen studies were included, containing 3 887 156 participants and 11 614 cases. In categorical analysis for the relationships between abnormal weight and BMI, the summary risk ratio (RR) of brain tumors was 1.34 (95% confidential interval (CI), 1.15-1.56) for obesity, 1.12 (95% CI, 1.05-1.19) for overweight and 0.77 (95% CI, 0.64-0.93) for underweight; the summary RR of gliomas was 1.13 (95% CI, 1.02-1.26) for overweight and 0.71 (95% CI, 0.58-0.88) for underweight; the summary RR of meningiomas was 1.48 (95% CI, 1.30-1.69) for obesity and 1.18 (95% CI, 1.07-1.31) for overweight. In dose-response analysis, for every 5 kg/m(2) increment of BMI, the summary RR was 1.13 (95% CI, 1.07-1.20) for overall brain tumors, 1.07 (95% CI, 0.97-1.19) for gliomas and 1.19 (95% CI, 1.14-1.25) for meningiomas.

CONCLUSIONS

Excess weight was associated with increased risk of brain tumors and meningiomas but not with gliomas. Selective screening for brain tumors among obesity, especially for the females, might be more instructive.