A case-control study of element levels and cancer of the upper aerodigestive tract.

A population-based case-control study was conducted in western Washington state to investigate possible dietary risk factors for laryngeal, esophageal, and oral cancers. Using results from a food frequency questionnaire, past dietary intakes of iron, zinc, and calcium were estimated for 661 cases and 466 controls. Clippings were also taken from the nails of both halluces to determine concentrations of iron, zinc, calcium, chromium, and cobalt in 507 of the cases and 434 of the controls. After adjustment for smoking, alcohol, and dietary beta-carotene and vitamin C intake, individuals who reported dietary intakes of iron and zinc in the upper quartile were less likely to develop cancers of the larynx and esophagus than were individuals with intakes in the lowest quartile [odds ratios (OR), 0.5 for iron and 0.1 for zinc]. However, there were no significant differences in zinc concentrations in nail tissue between subjects with these types of cancer and controls. Esophageal cancer cases had higher nail concentrations of iron and calcium than did controls (OR, 2.9 for high versus low quartiles of iron; OR, 2.6 for high versus low quartiles of calcium). Individuals who developed esophageal or oral cancer were more likely to have elevated cobalt concentrations in their nail tissue than were individuals without cancer (OR, 9.0 and 1.9 respectively, for high versus low quartiles). The results of this study suggest that there may be differences in mineral intake or metabolism between individuals who develop some carcinomas of the upper aerodigestive tract and those who do not.