Human brain tumors and exposure to metal and non-metal elements: a case-control study.

ABSTRACT

BACKGROUND: Primary brain tumors are among the most deadly of all cancers, with a 1-year survival rate of 52%. Certain elements, such as nickel, cadmium, chromium, arsenic, and beryllium, are established carcinogens in other organs. Silicon and titanium are suspected carcinogens and other elements are known to promote or inhibit the rate of tumor growth. Knowledge about the carcinogenicity of these elements in the brain is limited. In this study, we investigated the potential role of these elements as risk factors for human brain tumors. METHODS: In a case-control study, we assessed brain biopsies from 12 patients with various types of primary brain tumors and in tumor-free brain tissue from 6 autopsy cases. We used energy-dispersive X-ray analysis (EDX) to determine if there were significant differences in the concentration of the study elements in tumors and in control brains. RESULTS: In a bivariate analysis, a statistically significant association was observed between the presence of brain tumors and the concentrations of silicon (p = 0.01), magnesium (p = 0.01), and calcium (p = 0.03). Zinc was also associated with a borderline significance (p = 0.05). No association was observed for nickel (p = 0.74). Although the magnitude of the observed association was estimated using multiple logistic regression analyses, the relative risk estimates were imprecise because of insufficient sample size. Further research using a larger sample size is needed to elucidate the role of these elements in human brain carcinogenesis.