An overview of the epidemiologic and pathologic significance of premalignant lesions of the stomach is presented, with correlations between cancer risk, prevalence of atrophic gastritis and environmental factors such as nitrate and food items. The protective role of lettuce and fresh vegetables is discussed. The diffuse type of gastric cancer appears to be less environmentally linked than the intestinal type, and it is hypothesized that the pathogenetic process may begin during the first decade of life. An analysis of precursor lesions and gastric cancer in various geographic regions of Columbia, South America is presented to illustrate these relationships.