EFFECTS OF VITAMIN MINERAL SUPPLEMENTATION ON THE PREVALENCE OF HISTOLOGICAL DYSPLASIA AND EARLY CANCER OF THE ESOPHAGUS AND STOMACH - RESULTS FROM THE DYSPLASIA TRIAL IN LINXIAN, CHINA

Linxian, China has some of the highest rates of esophageal/gastric car dia cancer in the world, and epidemiological evidence suggests that ch ronically low intake of micronutrients may contribute to these high ca ncer rates. To examine whether supplementation with multiple vitamins and minerals can affect the occurrence of esophageal/gastric cardia ca ncer in this population, a two-arm randomized nutrition intervention t rial was conducted among 3318 Linxian residents with cytological evide nce of esophageal dysplasia. During the 6-year intervention, esophagea l/gastric cardia cancer mortality was 8% lower among those receiving t he active supplements. After 30 and 72 months of intervention, endosco pic surveys were carried out to see if the nutritional supplements had affected the prevalence of clinically silent precancerous lesions and early invasive cancers of the esophagus and stomach. In the first sur vey, in 1987, 833 subjects were endoscoped; in the second survey, in 1 991, 396 subjects were examined. The histological diagnoses from each survey were compared by treatment group. Cancer or dysplasia was diagn osed in 28% of the subjects endoscoped in 1987 and 24% of those examin ed in 1998. The odds ratio for subjects in the treatment group (versus those in the placebo group) having esophageal or gastric dysplasia or cancer was 0.84 (95% confidence interval, 0.61-1.15) in 1987 and 0.86 (0.54-1.38) in 1991. Although modest protective effects on worst over all diagnosis were seen in the supplemented group in both surveys, non e of the results was statistically significant, and the findings must be considered inconclusive. It is likely that longer interventions and larger numbers of endoscoped subjects will be required to fully inves tigate the effects of micronutrient supplementation in this population .