The incidence and mortality of gastric cancer havefallen dramatically in US and elsewhere over the pastseveral decades.Nonetheless,gastric cancer remains amajor public health issue as the fourth most commoncancer and the second leading cause of cancer deathworldwide.Demographic trends differ by tumor locationand histology.While there has been a marked declinein distal,intestinal type gastric cancers,the incidence ofproximal,diffuse type adenocarcinomas of the gastriccardia has been increasing,particularly in the Westerncountries.Incidence by tumor sub-site also varieswidely based on geographic location,race,and socio-economic status.Distal gastric cancer predominates indeveloping countries,among blacks,and in lower socio-economic groups,whereas proximal tumors are morecommon in developed countries,among whites,and inhigher socio-economic classes.Diverging trends in theincidence of gastric cancer by tumor location suggestthat they may represent two diseases with differentetiologies.The main risk factors for distal gastric cancerinclude Helicobacter pylori(H pylori)infection anddietary factors,whereas gastroesophageal reflux diseaseand obesity play important roles in the development ofproximal stomach cancer.The purpose of this review isto examine the epidemiology and risk factors of gastriccancer,and to discuss strategies for primary prevention. The incidence and mortality of gastric cancer have dramatically changed in US and elsewhere over the past weeks. Nonetheless, gastric cancer remains amajor public health issue as the fourth most common cancer and the second leading cause of cancer deathworldwide. Demographic trends differ by tumor location and histology. While there has been been marked decline in distal, intestinal type gastric cancers, the incidence of particles, diffuse type adenocarcinomas of the gastric cardia has been increased, particularly in the Western countries. Incidence by tumor sub-site also varywidely based on geographic location, race, and socio- economic status. Dysal gastric cancer predominates indeveloping countries, among blacks, and lower socio-economic groups, of proximal tumors are more common in registered countries, among whites, and inhigher socio-economic classes. Dogging trends in the incidence of gastric cancer by tumor location suggestthat they may represent two diseases with differentetiologies.The main risk factors for distal gastric cancerinclude Helicobacter pylori (H pylori) infection and dispensary factors, but gastroesophageal reflux disease and obesity play important roles in the development of proximal stomach cancer. The purpose of this review is to examine the epidemiology and risk factors of gastriccancer, and to discuss strategies for primary prevention.