An approach to establishing N-nitroso compounds as the cause of gastric cancer.

Although gastric cancer is the most common cause of mortality from cancer, its etiology is not yet clear. To elucidate the role of N-nitroso compounds, we investigated 30 cases of gastric cancer by determination of the contents of nitrate and ascorbic acid and by detection of mutagens in urine. Cases were paired 1:1 with patients with dysplasia and normal controls of the same sex and age group. In comparison with normal controls, the gastric cancer group had higher nitrate and lower ascorbic acid levels in urine. Mutagenicity was observed in the urines of 83.3% of the gastric cancer cases and in 16.6% of the dysplasia group, but in none of those from normal controls. When the N-nitroso compound content of gastric juice was determined, the levels in control subjects were significantly lower than those in persons with gastric cancer. These results support the hypothesis that the cause of gastric cancer may be N-nitroso compounds.