H. pylori infection and gastric cancer: state of the art (review).

Gastric cancer (GC) is one of the leading types of cancer worldwide, particularly in East Asian populations. Helicobacter pylori (HP) infection has been established as a major risk factor for GC. Although more than 50% of the world population is infected with this bacterium, less than 2% develop GC. Therefore, further risk factors (such as host genetic polymorphisms and lifestyle, as well as environmental and epigenetic factors) may also play a role in its occurrence. The correlation between HP infection and GC represents a typical model of a multi‑step process, characterized by some pre-neoplastic lesions with a high risk of progression (atrophic gastritis, intestinal metaplasia and dysplasia). In addition, HP also plays an oncogenic role in the development of mucosa‑associated lymphoid tissue (MALT) lymphoma, that accounts for approximately 3% of all gastric tumors. Hyperplastic polyps often arise in patients with atrophic gastric mucosa and HP‑associated gastritis (25% of cases); however, their malignant transformation is rare (<3% of cases). A number of trials have demonstrated the possibility of cancer prevention through HP screening and eradication, particularly in high‑risk populations, whereas it may not be cost‑effective in areas of low risk. In this review, we discuss i) the complex pathogenetic mechanisms of gastric carcinogenesis in which HP is involved; ii) the main approaches to the diagnosis, prevention, surveillance and treatment of pre-malignant lesions associated with HP infection; iii) the most effective way to detect GC in its earlier stages; and iv) the most important contribution to reducing the burden of GC.