Understanding Cancer and H Pylori
Helicobacter pylori, or H. pylori, is a spiral-shaped, gram-negative bacterium that is oral-bourne -- meaning that it enters to body through the mouth. In many people, it can reside in the mucus layer that coats the inside of the human stomach which would then produce an ulcer. In most, it leaves the stomach causing CANCER and/or HEART DISEASE.
A Sneaky Survival Mechanism
To survive in the harsh, acidic environment of the stomach, H. pylori secretes an enzyme called urease, which converts the chemical urea to ammonia. The production of ammonia around H. pylori neutralizes the acidity of the stomach, making it more hospitable for the bacterium. If a person has adequate HCl production in the stomach, the chance of H. pylori being able to take hold and proliferate is slim. Decreased HCl and digestive enzyme production, commonly caused by eating a typical American diet, sets an individual up for a local and/or systemic infection. In addition, the helical shape of H. pylori allows it to burrow into the mucus layer, which is less acidic than the inside space, or lumen, of the stomach. H. pylori can also attach to the cells that line the inner surface of the stomach.
Although immune cells that normally recognize and attack invading bacteria accumulate near sites of H. pylori infection, they are unable to reach the stomach lining. In addition, H. pylori has developed ways of interfering with local immune responses, making them ineffective in eliminating this bacterium.
H. pylori and Cancer
Epidemiologic studies have shown that individuals infected with H. pylori have an increased risk of gastric adenocarcinoma. According to the WHO, it is the number one cause of stomach cancer worldwide. The risk increase appears to be restricted to non-cardia gastric cancer. For example, a 2001 combined analysis of 12 case–control studies of H. pyloriand gastric cancer estimated that the risk of non-cardia gastric cancer was nearly six times higher for H. pylori-infected people than for uninfected people.
Additional evidence for an association between H. pylori infection and the risk of non-cardia gastric cancer comes from prospective cohort studies such as the Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study in Finland. Comparing subjects who developed non-cardia gastric cancer with cancer-free control subjects, the researchers found that H. pylori-infected individuals had a nearly eightfold increased risk for non-cardia gastric cancer.