[The effect of riboflavin, molybdenum, selenium and zinc on the development of induced tumors of the esophagus and forestomach in rats].

The study was concerned with the influence of prolonged treatment with riboflavin, molybdenum, selenium and zinc on the induction of tumors of the esophagus and forestomach by N-nitrososarcosine ethyl ester (NSEE) in rats. Riboflavin was fed whereas molybdenum, selenium or zinc were given in drinking water after the discontinuation of treatment with NSEE, once hyperplasia and dysplasia became evident in the mucous membrane of the esophagus and forestomach. Riboflavin and molybdenum decreased the incidence of carcinoma and multiplicity of papilloma of the organs. Selenium and zinc did not affect the carcinogenesis in the organs discussed.