The epidemiology of diet and cancer

Influence of experimental diets on hepatic glutathione levels in rats with methylnitrosourea-induced mammary carcinoma

Mammary tumor development induced by methylnitrosourea in female Sprague-Dawley rats had no significant effect on hepatic glutathione levels. If the diets of methylnitrosourea-treated animals were supplemented with vitamin A and E an increased hepatic glutathione level was observed initially. A high fat diet (21% per weight) supplemented with the two vitamins led to a decreased hepatic glutathione level 2 months after tumor induction. Advanced tumor development under any of the diets tested had no effect on hepatic glutathione.

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.