Stomach cancer

   Epidemiology. Morbidity   Despite the steady decline of stomach cancer, he remains one of the most common forms of human cancer. Annually in the world become sick with gastric cancer more than 1 million people. Stomach cancer is heterogeneous and varies greatly in different countries and regions, indicating that the impact of climatic, domestic, food and other factors on its occurrence. The maximum incidence of gastric cancer in the world was seen in men in Japan (114.7 per 100 000 population) and the minimum - in white U.S. women (3.1 per 100.000). High incidence of gastric cancer registered in China, Belarus, Russia, Estonia, Latvia, New Zealand (Maori).The greatest number of patients with stomach cancer are between the ages of 50 to 60 years, from ages 40 to 50 years account for 25% of the total number of cases, men are sick 2 times more often than women.   Contributing factorsFactors determining the incidence of stomach cancer, linked to socio-economic standard of living. Stomach cancer is much more prevalent among the poor and less - to secured. For the development of gastric cancer are of particular importance nature diet and lifestyle in the first two decades of life.To exogenous risk factors for gastric cancer is primarily a diet with an excess of salt, as salt fish, meat, vegetables, seafood, causing osmotic damage to the epithelium and contributes to the population of the mucous membrane of the stomach bacteria Helicobacter pylori (H. pylori). The risk of developing stomach cancer increases with the prevalence of food carbohydrates, with a deficiency of vitamins and minerals.Great importance in the occurrence of gastric cancer has a chemical composition of soil and water in the area of human habitation, which primarily related to the content of nitrites and nitrates, which in the stomach with the participation of microorganisms become nitrosamines, which are powerful carcinogens. By significantly increasing the risk of gastric cancer is, and smoking. A role can also play an alcohol and, especially, surrogate distilleries products.Endogenous factors contributing to the development of gastric cancer include: duodenogastric reflux, intragastric formation of endogenous substances such as nitroso compounds, the violation of absorbability and increased utilization of vitamins and trace elements, genetic and immunological factors, which provided that the protective mucosal barrier in the stomach does not possess any carcinogenicproperties.

Initiating factors of carcinogenesis in the stomach are the products of free radical reactions, which are formed during inflammation: the radicals of oxygen, nitrogen compounds. Antioxidants (vitamins A, C, E, B6, beta-carotene, folic acid, trace elements: selenium, zinc) prevents the formation of free radicals, inhibit nitrosation and therefore have a protective effect and thus prevent the development of cancer.Drinking large amounts of fresh fruits, vegetables, vitamin E, green tea reduces the risk of gastric cancer.Currently, proved the role of hereditary susceptibility to the carcinogenic effects in the development of gastric cancer. The genetic component accounts for up to one third of cases of stomach cancer. Hereditary factors are associated primarily with the diffuse type of gastric cancer. In direct relatives of patients with diffuse type of gastric cancer risk of getting above 6 times. Diffuse type gastric cancer is more commonly associated in patients with blood group A (P), and in some regions - with the group 0 (1).Special role in gastric carcinogenesis is the bacterium H. pylori. Epidemiological studies indicate a logical link between infection with H. pylori and gastric cancer.Thus, in the high incidence of gastric cancer H.pylori infection is much higher than in groups with low morbidity them. The frequency of infection in developed countries is about 15% of the population in less developed countries - up to 100%. In those populations where infection has decreased H. pylori, has also decreased the incidence of stomach cancer.In 1994, the International Agency for Research on Cancer, WHO drifted in the bacterium Helicobacter pylori to carcinogens first class, and identified it as the cause of stomach cancer in humans.From H. pylori binds 2,7-12-fold increased risk of gastric cancer in humans.According to epidemiological data, with the colonization H. pylori may be linked to 75% of all cases of gastric ACOM in developed countries and about 90% in developing countries. It is now also established that infection with H. pylori with gastric MALT-lymphoma.Compared with other infectious agents (eg, E. coli, Salmonella strains) H. pylori does not possess pronounced pathogenic properties. Occupying a particular ecological niche, a microbe in a lifetime is able to persist in the stomach of the host, without causing a considerable breakdown of the mucous membrane. During prolonged colonization of the stomach mucosa obochlochki H. pylori, causing inflammation, induces the development of mutations and genome rearrangements germintativnyh cell necks of the glands and the bottom of the pits.The pathogenesis of the initiating effect of H. pylori on gastric mucosa is complex.Facts about the absence of H. pylori in areas of dysplasia of the gastric mucosa, as well as the inability of H. pylori reduce nitrate and produce precursors of carcinogenic N-nitroso compounds is not possible to draw conclusions about their direct carcinogenic effect.Continuous damage to the protective mucosal barrier of the stomach facilitates access of carcinogens to cells and germinal zones and induction bkteriyami H. pylori epithelial proliferative changes with the activation of proto-oncogenes and the genetic instability of the stem cells. This proves quite catalytic role of these bacteria in the process of carcinogenesis, and antibiotic therapy aimed at eradication of H. pylori, may lead to the elimination of major risk factors for gastric malignant transformation.H. pylori promotes the formation of precancerous lesions and conditions that are intermediate stages of carcinogenesis in the stomach. Long-term persistence of these bacteria in the gastric mucosa in the presence of genetic predisposition creates the conditions for the implementation of the carcinogenic potential of various environmental factors, which, after the induction phase of initiation are involved in later stages of tumor transformation

From the beginning of chronic gastritis, the infection is H. pylori, before the development of atrophic and dysplastic changes in the gastric mucosa in the middle is 30-40 years, which suggests that the conditions for carcinogenesis in the stomach are formed in childhood. Given that disregeneratornye changes when infected with H.pylori develop, at least for two or three decades, as well as the slow growth of the tumor with a long, silent clinical course, special attention should be given to practitioners of contingent child infected with H. pylori. The key to solving the problem of stomach cancer in general is the prevention and treatment of helicobacter gastritis and H. pylori associated diseases in children and young people.