Gastric cancer and Helicobacter pylori infection

The Nobel prize in Physiology and Medicine in 2005 was presented to Barry Marshall and Robin Warren for their discovery of Helicobacter pylori (Hp), but only the involvement of this germ in gastritis and peptic ulcer has been mentioned in the award sentence, while numerous epidemiological, clinical and experimental studies and reports emphasized the crucial role of Hp in pathogenesis of gastric cancer (GC). This review is based on the old concept proposed by P. Correa much before the discovery of spiral bacteria in the stomach, postulating the cascade of mucosal changes from acute/chronic gastritis into the atrophic gastritis with intestinal metaplasia and finally to dysplasia and GC. It is now widely accepted view that Hp infection is the major initiator of the inflammatory and atrophic changes in gastric mucosa accompanied by an over-expression of certain growth factors such as gastrin as well as of cyclooxygenase-2 (COX-2) and anti-apoptotic proteins including survivin and B-cl(2), leading to proliferation of mutated atrophic cells, excessive angiogenesis, inhibition of apoptosis and formation of gastric tumour. All the morphological and biochemical changes associated with the transformation of mucosal cells into the cancer cells can be traced in excellent experimental model of gastric cancerogenesis induced by infection of Hp in Mongolian gerbils. Since the eradication therapy was proved in several prospective clinical trials to greatly reduce the incidence of GC and this was confirmed on the gerbil model of Hp-induced GC, it has been postulated; a) that Hp is the major causal factor in pathogenesis of GC and b) that the only rational approach in attempt to reduce the occurrence of GC is the global eradication of Hp.