Dietary and tobacco risk factors for adult onset glioma in the San Francisco Bay Area (California, USA)

The roles of diet and tobacco in the etiology of primary brain cancer are controversial. In this report, we compare dietary and cigarette smoking histories among 434 adults newly diagnosed with glioma in the San Francisco Bay Area (California, USA) between 1991 and 1994 with frequency age, gender, and ethnicity-matched population-based controls. Data were obtained on use of vitamin supplements and mean weekly consumption of each of 24 food groups. Adjusted for age, family income, and education, for both men and women, cases had higher mean weekly consumption of cured meats and other cured foods, lower consumption of high vitamin A and C fruits and vegetables, and higher average intakes of beer and other alcohol than controls. Men with brain cancer were twice as likely as control men to report high consumption of cured foods and low consumption of foods rich in vitamin C (odds ratio [OR]=2.0, 95 percent confidence interval [CI]=1.2-3.5). This association was less pronounced and not statistically significant in women (OR=1.5, CI=0.8-2.7). Similarly, men with brain cancer were twice as likely as controls to have high nitrite and low vitamin C consumption. Among men only, cases were 1.8 times more likely than controls to report smoking unfiltered cigarettes (CI=0.9-3.4). Moreover, among smokers, cases smoked unfiltered cigarettes almost twice as long as controls (P=0.04) and cases' average total pack-years also significantly exceeded controls. Although these findings support the hypothesis that N-nitroso compounds might be a factor in adult glioma, they are compatible with other dietary hypotheses. In particular, these results also favor the hypothesis that total body burden of oxidants may play a role in brain cancer causation.