The results of a survey of a population with a high risk of oral and
esophageal cancer and the outline of a
chemoprevention scheme for persons found to have a
precancerous condition of the mouth and esophagus are presented. Of a total of 1,569 men examined, 11% had preleukoplakia and
leukoplakia of the mouth, and 60% of the 1,344 men in whom esophagogastroscopy was performed had chronic
esophagitis. The relative risk of
oral leukoplakia was highest (11.5) among men who
smoke and use nass quid. The relative risk was also elevated for persons who only use nass quid (5.6) or who only
smoke cigarettes (7.8). Nass use had no effect on the risk of
esophagitis. A slight elevation of risk (1.9) of
esophagitis was observed for current smokers and drinkers. Of the men from whom blood was drawn for analysis, 4%, 66%, and 86% had low levels of
retinol,
carotene, and
riboflavin, respectively. The high prevalence of oral and esophageal
precancerous conditions and low blood levels of
riboflavin,
carotene, and
vitamin A observed in the surveyed population, as well as the existing evidence on the possible protective effect of these nutrients in
carcinogenesis, provide an opportunity and a justification for the chemopreventive trial, with the regression of observed precancerous lesions as the end point of the study.