The epidemiology of gastric cancer.

The epidemiology of gastric cancer is remarkable for both its dramatic decline in incidence over the past century and its continuing presence as the second leading cause of cancer deaths worldwide despite this decline. Factors including increased consumption of fruits and vegetables, and decreased intake of salty foods have largely been credited for the decline. Epidemiologic studies continue to provide data on other gastric cancer risk factors, including associations with Helicobacter pylori infection, as well as dietary factors, tobacco, and alcohol intake. In response to the opposing trends of decreasing distal gastric cancer and increasing gastric cardia adenocarcinoma, studies are beginning to identify gastric cancer risk factors separately by tumor subsite. Future epidemiologic studies that include information on site of origin as well as molecular markers promise to yield more homogeneous classification of case groups, which will enhance identification of underlying disease processes.