The Etiology of Gastric CancerIntragastric Nitrosamide Formation and Other Theories

Abstract

Possible etiologic agents for human gastric cancer (GC) are reviewed, especially nitrosamides that might be produced intragastrically from nitrite. The metabolism of nitrite and nitrate is surveyed, including the correlation between nitrate intake and GC mortality in 12 countries. The negative correlation between GC incidence and fresh fruit and vegetable intake is examined; this correlation may be due to inhibition of nitrosamide formation by ascorbate and polyphenols. GC-associated foods are listed, including dried, salted fish and meat products and fava beans, treatment of which with nitrite yields mutagens and nitroso-methylurea. Also discussed is whether cimetidine treatment produces GC; the association of GC with high-starch diets and highly salted foods; the question of whether nitrosamides are produced and act in the normal or achlorhydric stomach; the falling GC rate in the United States; and the association of GC with soft water, peaty soils, and certain industries and occupations. Practical measures are suggested for reducing GC incidence.