The epidemiology of gastric cancer.

Gastric cancer mortality has declined markedly around the world. In South Australia, the reduction approximated 40% over the last 20 years. Possible reasons include: better refrigeration; reduced consumption of salted, smoked, and chemically preserved foods; increased intake of fruit and vegetables; and improved living standards and a greater use of antibiotics, which may have reduced Helicobacter pylori infection. Reductions generally have been greater for intestinal than diffuse histopathologies. Gastric cancer remains the second leading cause of cancer death worldwide, probably accounting for about 10% of newly diagnosed cancers. High rates apply to Japan, China. Central and South America, Eastern Europe, and parts of the Middle East, and low rates to North America, Australia and New Zealand, Northern Europe, and India. Rates usually are higher in lower socioeconomic groups. Five-year relative survivals of around 20% or less are frequently reported. A figure of 50% or more has been cited for Japan, where there has been radiological screening, although this exceptional figure could have been affected artificially by lead-time and related effects. Male-to-female incidence ratios generally are in the 1.5-2.5 range, with higher ratios for intestinal than diffuse cancers and higher-risk populations. In South Australia, the ratio has been 1.8 to one, although higher at 4.6 to one for cardia lesions. Recent increases in cardia cancers, especially in males in populations of European extraction, often are accompanied by increases for esophageal adenocarcinoma. It is estimated that the global burden of gastric cancer could be reduced by up to 50% by dietary changes that included an increased intake of fruit and vegetables.