Etiology of gastric cancer

The development of gastric cancer can be due to many reasons, its multifactorial etiology is more likely . It can be assumed that the development of a malignant tumor of the stomach includes histological changes starting from atrophy of the gastric mucosa with the subsequent development of metaplasia, dysplasia and malignant changes.
Genetic factors play a significant role in the occurrence of stomach cancer. Examples of the genetic inheritance of the disease have been observed for centuries, the Bonaparte family is the most significant in this regard: Napoleon, his father Charles, grandfather Joseph, and several descendants of Napoleon died of stomach cancer. Patients with hereditary non-polypous colorectal cancer (Lynch II syndrome), an autosomal dominant disease with a high degree of penetrance, have an extremely high risk of developing stomach cancer. In addition, the risk of developing the disease in immediate families of patients with gastric cancer is 2-3 times higher. The high frequency of gastric cancer, mainly of the diffuse type, in patients with blood group A (P) also speaks in favor of genetic factors. Prospective clinical studies have shown that infection with H. pylori leads to a 3-6-fold increase in the incidence of gastric cancer, mainly of the intestinal type, located in the distal third of the stomach. However, it was not possible to prove the role of peptic ulcer due to H. pylori in the onset of cancer, therefore, the colonization of H. pylori plays an independent role in the development of these two forms of pathology. The prevalence of atrophic gastritis and intestinal metaplasia among populations of people in regions with a higher incidence of gastric cancer has been proven. B12-deficient anemia leads to a three-fold increase in the risk of developing cancer, which is probably due to a prolonged decrease in gastric acidity, hypergastrinemia and neuroendocrine hyperplasia. The inverse relationship between the incidence of gastric cancer and socioeconomic status is obvious. It is likely that overpopulation, poor sanitary conditions, and inadequate canning are important. Tobacco smoking , some dietary risk factors (excessive consumption of salty, smoked foods, lack of diet of vegetables and fruits), excessive consumption of alcoholic beverages, poor food storage conditions can lead to stomach cancer. Studies in Japan showed that a decrease in the incidence of gastric cancer occurred in parallel with a decrease in the consumption of salted and dried foods and an increase in the consumption of fresh vegetables and fruits. Foods that are high in nitrite and nitrate, which were previously used to store meat, fish, and vegetables, induce the development of a stomach tumor in animals. Anaerobic bacteria colonizing the atrophied gastric mucosa contribute to the conversion of nitrites and nitrates into TV nitroso compounds , which have a carcinogenic effect. The use of food cooling and the improvement of their preservation methods helped to reduce the incidence of gastric cancer. An increase in vitamin C in food can play a protective role. Controversial is the etiological role in the development of gastric cancer of factors such as benign gastric ulcers, glandular polyps of the bottom of the stomach, hyperplastic polyps. Distal gastrectomy is associated with a high risk (2-3 times) of the development of gastric cancer. In this case, the disease occurs 20-30 years after surgery – the period necessary for the development of intestinal metaplasia, dysplasia and cancer under the influence of prolonged achlorhydria and enterogastric reflux after resection of the stomach. It should be noted the differences in the etiology of distal and proximal gastric cancer and the need for further epidemiological studies to determine the causes of these various diseases.

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