Risk factors for cancer development in helicobacter pylori gastritis.

Despite the progressive decline in incidence in the last 50 years, gastric cancer continues to be the most frequent neoplasia in Asia and some Latin American countries, and is the second most common fatal neoplasia in the world. The discovery, in 1983, of gastric infection by Helicobacter pylori (H. pylori) represents a very important step that has contributed to the understanding of the natural history of gastric cancer. Indeed, the results of epidemiological and experimental animal studies clearly show a strong association between H. pylori infection and gastric cancer. H. pylori is one of the most frequent infections, affecting about 60% of the world-wide population, and may persist for several decades without appropriate therapy. The majority of infected individuals suffer from asymptomatic chronic gastritis and only a small minority of them develop gastric cancer (life time risk 0.1%) s. Nowadays, H. pylori is defined as a first-class gastric carcinogen but the mechanisms involved in tumor initiation and progression are still unclear. Factors claimed to be implicated are H. pylori strain, genetic make-up of the host, immune response, age at the time of infection and other environmental factors.