Future inquiries into the epidemiology of gastric cancer.

The fact that gastric cancer has been shown in many studies to be strongly related to a large number of social factors, ethnic background, occupation, socioeconomic status, and the like, suggests the importance of exogenous factors in its etiology. Past studies show a variety of relationships that furnish leads requiring elucidation to further understanding of this disease, e.g., higher risks related to exposures to asbestos, metals dusts, purgatives, and poor dental hygiene. Diet inquiries have steadily improved and negative relationships have been discovered with ingestion of vegetables in studies in Wales, Liverpool, Buffalo, Honolulu, Japan, and Norway. Positive relationships with starch have been found in many of these same places as well as in Israel. These leads need further investigation, as do better methods of diet research, studies of diet and histological type of gastric cancer, diet in its relationship to familial aggregation of gastric cancer, and studies of consistencies in relationships among the various sites in the digestive tract. Because diet is so heterogeneous in modern societies, multivariate analysis is needed in addition to simpler traditional modes.