Coffee, tea, caffeine intake, and risk of adult glioma in three prospective cohort studies.

Current data suggest that caffeinated beverages may be associated with lower risk of glioma. Caffeine has different effects on the brain, some of which could play a role in brain carcinogenesis, and coffee has been consistently associated with reduced risk of liver cancer, thus suggesting a potential anticarcinogenic effect. A total of 335 incident cases of gliomas (men, 133; women, 202) were available from three independent cohort studies. Dietary intake was assessed by food frequency questionnaires obtained at baseline and during follow-up. Cox proportional hazard models were used to estimate incidence rate ratios (RR) and 95% confidence intervals (CI) between consumption of coffee, tea, carbonated beverages, caffeine, and glioma risk adjusting for age and total caloric intake. Estimates from each cohort were pooled using a random-effects model. Consumption of five or more cups of coffee and tea daily compared with no consumption was associated with a decrease risk of glioma (RR, 0.60; 95% CI, 0.41-0.87; P(trend) = 0.04). Inverse, although weaker, associations were also observed between coffee, caffeinated coffee, tea, and carbonated beverages and glioma risk. No association was observed between decaffeinated coffee and glioma risk. Among men, a statistically significant inverse association was observed between caffeine consumption and risk of glioma (RR, 0.46; 95% CI, 0.26-0.81; P(trend) = 0.03); the association was weaker among women. Our findings suggest that consumption of caffeinated beverages, including coffee and tea, may reduce the risk of adult glioma, but further research is warranted to confirm these findings in other populations.