Dietary pattern analysis: a different approach to analyzing an old problem, cancer of the esophagus and stomach

Abstract

The roles that some foods and dietary components may play in the etiology and pathogenesis of cancer of the esophagus and stomach have been recognized for several years. Most of the evidence for those roles has come from ecologic, descriptive studies, as well as from case-control and cohort-type studies. Although both tumor sites are part of the digestive system, the pathogenesis of the tumors and their relation to specific dietary components may differ. In the past 40 y, the type of tumor most commonly found in the esophagus has changed. Although 40 y ago 90% of all esophageal tumors were of the squamous cell type, the incidence of esophageal adenocarcinoma has risen such that today it is more prevalent than the squamous cell type in the United States and Europe (1). The epidemiology of these types of tumors varies markedly, and thus, one may predict that dietary components have different effects on the risks of these cancers. However, many dietary factors, such as the type and amount of food, preparation method, and energy intake, can affect risk. Some of these factors may be considered in the design of a human study whereas others may not. Other factors to consider include sex and race. Deaths from cancer of the esophagus are > 3 times more common in men than in women (2). Moreover, squamous cell cancer is 6 times more likely to occur in black men than in white men. Risk factors associated with the development of squamous cell cancer are well documented in medical texts, and several of those risk factors are dietary. For example, squamous cell cancer of the esophagus is strongly associated with excess alcohol consumption. In addition, the combined use of tobacco, in any of its forms, tends to greatly enhance the risk of developing this cancer. In contrast, diets high in fruit and vegetables are associated with a decreased risk of squamous cell cancer of the esophagus. What might be considered a high level of consumption? Probably 5 servings of fruit and vegetables/d would be considered high because only 23.9% of US adults eat that amount. In Nebraska, only 17.6% of adults consume 5 servings/d (2). Although several health organizations have recommended that level of daily consumption and two-thirds of US adults believe that a diet containing fruit and vegetables is very important, consumption has increased only slightly in the past 30 y (2). What specific components of fruit and vegetables are associated with the reduction in the risk of squamous cell cancer of the esophagus? The components may be vitamin C and carotenoids because high intakes of those compounds may decrease the risk. At the same time, the evidence concerning the relation between meat and dairy products and the risk of esophageal cancer