Epidemiology of gastric cancer.

Despite a dramatic reduction in incidence and mortality rates, gastric cancer (GC) was still recently the second most common neoplastic cause of death worldwide. GC treatment has not been substantially improved and screening programmes have not proven feasible outside Japan. On the other hand, primary prevention of GC is hampered by the lack of a single specific causal factor, even if diet has been shown to play a relevant role in its etiology. A large number of studies have indicated that salted/smoked and pickled/preserved foods (rich in salt, nitrites and preformed nitrosocompounds) are associated with an increased risk of GC. In contrast, a high consumption of fresh fruit and raw vegetables and a high intake of antioxidants have been shown to reduce the risk of GC. Domestic refrigeration and a reduced use of salt contribute to explain the decreasing temporal trend and the geographical patterns of GC. Results of human chemoprevention trials are encouraging but have not been confirmed. Evidence of an association between Helicobacter pylori infection and GC has been recently provided, even if several aspects of GC epidemiology do not fit in this hypothesis. Studies on H. pylori eradication and its effects on GC risk represent a priority for future research in view of the potential preventive applications.