[Effects of nitrate and ascorbic acid on carcinogenesis in the operated rat stomach].

In the last few years, a great deal of attention has been paid to the hypothetical relationship between high nitrate intake, N-nitroso-compounds and gastric cancer. This long term study deals with the effect of nitrate and ascorbic acid contained in drinking water on the development of cancer in operated stomachs of rats without additional application of a carcinogen (tumor model). A total of 147 F1-Hybrids of WELS/Fohm X BD IX--rats were subjected to stomach operation (Gastroenterostomia antecolica anterior, truncular vagotomy and pyloroplasty). Carcinomas in stomach occurred within 33 weeks (post operationem). The surgical procedures altered the gastric flora, resulting in an increase and predominance of nitrate-reducing bacteria. The maximal tumor rate (10 of 13 rats) occurred in rats with gastroenterostomy and additional nitrate exposition. It may be possible, the nitrate is a precursor of gastric carcinogenesis. But we could not give any significant evidence of this fact. The addition of ascorbic acid to the drinking water lead to a suppression of the development of tumors. Our experience with the tumor model "operated stomach" underline the multifactorial genesis of stomach cancer in rats.