Chemoprevention of oral and esophageal cancer in Uzbekistan, Union of Soviet Socialist Republics.

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.

Survey of a population with a high incidence of oral and oesophageal cancer.

The results of a survey of a population with a high incidence of oral and oesophageal cancer are presented. The population under study appears to have several epidemiologic characteristics, some of which may be associated with a high incidence of oral and oesophageal cancer. A remarkably high proportion (41%) of the men surveyed were nass users and this habit, like the use of other types of tobacco mixtures, has been related to oral cancer. Oral leukoplakia and chronic oesophagitis (conditions thought to be precursors of oral and oesophageal cancer) have been diagnosed in 11% and 60%, respectively, of the persons examined. Analysis of the relationship between nass use, cigarette smoking, oral leukoplakia and oesophagitis revealed that the prevalence of oral leukoplakia is highest among cigarette smokers who use nass. It appears that nass use does not affect the frequency of occurrence of chronic oesophagitis. However, a slight elevation of the prevalence odds ratio was observed for current smokers and drinkers. Biochemical analysis of the blood of a random sample of the surveyed population revealed low levels of riboflavin, vitamin A and carotenoids--vitamins that most probably have a protective effect against the development of cancer. The mutagenicity test has shown that nass contains a chemical or chemicals that exert a genotoxic effect. Chemical analysis revealed the presence in nass of tobacco-specific N-nitroso compounds.