The relationship between bacteria and tumor
Regarding the relationship between bacteria and tumors, there are many studies on Helicobacter pylori and gastric cancer.
Helicobacter pylori was first isolated from the gastric mucosa biopsy specimens of a chronically active gastritis patient by Australian scholars J. Robin, Warren and Barry, Marshall in 1983. It is an S-shaped or curved curved Gram-negative bacilli. The flagella on one end of the cell body allows the bacteria to easily pass through the gastric mucosa and settle to the gastric epithelial cells. It can also produce a large amount of urease and decompose urea in the cell An alkaline "ammonia cloud" is formed around it, which can resist the acidic environment in the stomach and prevent it from being killed by acid.
Humans are the only natural host for Helicobacter pylori. The infection rate of the population is very high, and the infection rate of the world's population is as high as 50%. The main transmission route of Helicobacter pylori is direct or indirect contact between people. This pathogen is spread through the digestive tract of the population, namely "mouth-mouth" and "feces-mouth". China is a country with high Helicobacter pylori infection, which may be related to the "mouth-to-mouth" transmission of shared eating utensils. For example, the habit of mothers chewing food and feeding them to babies also increases the chance of "mouth-to-mouth" transmission.
Helicobacter pylori infection mainly occurs in the stomach and duodenum medical education network | Collect and organize. Hp mainly causes chronic gastritis, gastric ulcer and gastric cancer. The mortality rate of gastric cancer in China ranks first among all types of cancer. Epidemiological data show that the incidence of gastric cancer is higher in some people with a high infection rate of Helicobacter pylori. However, there is no obvious relationship between rectal cancer, esophageal cancer, lung cancer and other tumors and the infection rate of H. pylori, thus demonstrating the pathogenic effect of H. pylori on gastric cancer. The World Health Organization has listed Helicobacter pylori as the first carcinogen of gastric cancer. Studies have shown that the positive rate of Helicobacter pylori in gastric cancer tissue is 69% to 95%; the incidence of gastric cancer in patients with Helicobacter pylori infection is 2.3% to 6.4%.
Helicobacter pylori is also associated with the occurrence of gastric mucosa-associated lymphoma. Because the incidence of this type of lymphoma in patients infected with Helicobacter pylori is 3.6 times greater than that of non-infected patients, eradicating Helicobacter pylori infection can reduce the incidence of this type of lymphoma or can make the tumor The development process is controlled. In addition, the taxonomically close Helicobacter pylori and Helicobacter pylori can cause similar lesions in mice.
However, the occurrence of gastric cancer is a long process, and it is the result of the combined effect of multiple factors. Gastric cancer also occurs in people without evidence of Helicobacter pylori infection. Evidence of how much the prevention and treatment of Helicobacter pylori infection affects the risk of gastric cancer is insufficient. The incidence of Helicobacter pylori infection and the incidence of gastric cancer are negatively correlated with socioeconomic status, and both increase with age. In the United States, the incidence of African Americans and Latinos is higher than that of Caucasians. It has been found that there is a regionally distributed correlation between H. pylori infection rate and gastric cancer mortality. However, men with stomach cancer are more likely than women, and there is no difference in the rate of H. pylori infection between the sexes. According to reports, some people have a high infection rate of H. pylori, but the incidence of gastric cancer is low. These circumstances indicate that other factors than Helicobacter pylori infection rate are also important in the risk factors of gastric cancer.
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