Gastric cancer and Helicobacter pylori

Abstract

SUMMARYGastric cancer is the second commonest cause of death from malignancy in the world. Its pathogenesis is comparatively well understood and its aetiology multifactorial. Non-cardia gastric cancer usually arises in a stomach that has been inflamed over a long period and where atrophy and intestinal metaplasia have supervened. The commonest cause of gastric inflammation is infection with Helicobacter pylori. Colonization with this organism increases the relative risk of developing this cancer by about six [Helicobacter and Cancer Collaborative Group. Gut 2001; 49: 347-53]. Its likelihood increases with the severity and extent of the gastritis. Severity is influenced by the virulence of the infecting organism, the genetics of the host, bile reflux, dietary factors and the presence of hypochlorhydria which influences the extent, as well as the severity, of the inflammation. The only predisposing factor which can easily be manipulated is H. pylori infection, which can be successfully treated in 80-90% of cases using a 1-week therapeutic regimen. INTRODUCTIONGastric cancer is the second commonest malignancy in the world and after lung cancer kills more people than any other malignant tumour.1 Although the incidence of the disease is falling in developed countries, changes in demography suggest that numbers dying from this condition will increase in the foreseeable future. The prognosis for gastric cancer once a diagnosis has been made is poor. In most developed countries only around 10% survive for 5 years. The only exception to these dismal statistics is Japan where, for a variety of reasons, the condition is often identified at an early stage and in younger and fitter patients. Preventative measures for gastric cancer are likely to be the most effective method of reducing the mortality from this disease and this in turn depends upon a knowledge of its aetiology. In recent years it has become apparent that the most important single factor responsible for the development of non-cardia gastric cancer (by far the commonest type) is infection with the organism Helicobacter pylori. This article addresses the relevance of this organism in the pathogenesis of gastric cancer and its interrelationship with other factors that predispose to the disease.Factors associated with gastric cancer Table 1 sets out the conditions known to be associated with gastric cancer. Considerable epidemiological research devoted to this disease shows that its incidence varies widely throughout the world and can differ markedly within individual countries. Although gastric cancer incidence has consistently fallen in developed countries, mortality rates remain high in the developing world. The disease is more common in the Far East than in the West and higher in Eastern and Central Europe than in Western Europe. It seems to be less common in Africa, but there are hotspots in South America. In general, the risk of cancer seems to be higher in those communities that are socio-economically disadvantaged, an exception to this rule being Japan. Wit...

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