Nutrition Intervention Trials in Linxian Follow-up Study

Two large, nutritional intervention trials were conducted in Linxian, China between 1985-1991. These trials tested the effect of multiple vitamins and minerals in the prevention of esophageal cancer in a population with the highest known rate for this disease in the world. Results from the trials showed that Beta-carotene + Vitamin E + selenium reduced total mortality, total cancer mortality, and stomach cancer incidence and mortality. Multivitamins/minerals also showed reduction in premalignant lesions. Preliminary follow-up data obtained for the time period after cessation of intervention in 1991 suggests that the observed benefit for total and cancer mortality is reduced but that the benefit for stomach cancer remains. The objectives of the follow-up study are: (1) to continue to determine cancer incidence and all causes of mortality in trial participants after intervention to permit examination of potential effects of the interventions on total and cause-specific mortality and cancer incidence in the post-intervention period; (2) to conduct a cross-sectional nutritional survey in a subsample of living trial participants to evaluate their nutritional status, asses the validity of dietary questionnaires, and relate neurologic status to vitamin B12 plasma levels; (3) to collect a blood sample from all living trial participants to permit further etiologic investigations of genetic and environmental hypotheses; and (4) to perform nested case-control studies of selected genetic and environmental hypotheses. To accomplish the objectives of the follow-up study, we will: (1) determine updated vital status and cancer status data on all trial participants via monthly checks of village doctor records and quarterly checks of the Linxian Cancer Registry; conduct a Vital/Cancer Status Interview Survey among all (n-34,000 trial participants (or their surrogates); identify, collect, and store all available diagnostic materials for trial participants identified as having develo