**H. pylori and Gastric Cancer: Molecular Epidemiology and Possibilities of Prevention**

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1897-1995.

120 Trends in Helicobacter pylori Infection

**Chapter 4**

**Molecular Epidemiology of** *Helicobacter pylori* **in**

**to Understand the Prognosis of the Disease**

Bruna Maria Roesler and

http://dx.doi.org/10.5772/58328

**1. Introduction**

aspect remains unclear.

José Murilo Robilotta Zeitune

Additional information is available at the end of the chapter

adenocarcinoma, and, possibly, extradigestive diseases.

Research on Cancer, World Health Organization.

**Brazilian Patients with Early Gastric Cancer and a Review**

*Helicobacter pylori* (*H. pylori*) is an universally distributed bacterium that affects more than half of the world population and is considered an important public health problem. Although colonization with *H. pylori* is not actually a disease, it is a condition that affects the relative risk of developing various clinical disorders of the upper gastrointestinal tract, as chronic gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT lymphoma) and gastric

Colonization with *H. pylori* virtually leads to infiltration of the gastric mucosa in both antrum and corpus with neutrophilic and mononuclear cells. Gastritis can be classified as an acute or chronic gastritis and it can involve all parts of the stomach or just the fundus, corpus or antrum. The chronic active gastritis is the primary condition related to *H. pylori* colonization, and other *H. pylori*-associated disorders, in particular, resulting from this chronic inflammatory process, as atrophic gastritis, causing an elevated risk of gastric cancer. Considering this association, in 1994 the bacterium was classified as a group I carcinogen by the International Agency for

Molecular techniques have revealed that *H. pylori* possesses a remarkable degree of genetic diversity, which could be responsible for its adaptation in the host stomach and for its pathological characteristics, in addition to the clinical outcome of the infection, although this

In Brazil, it is estimated that only about 10 to 15% of the gastric cancer cases are diagnosed at an early stage, aspect that directly impact the prognosis of the disease, which presents low

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