No one knows the exact causes of stomach cancer. Doctors seldom know why one person develops stomach cancer and another doesn't. Doctors do know, however, that people with certain risk factors are more likely than others to develop stomach cancer. Studies have found the following recognized risk factors for gastric cancer.
Helicobacter Pylori Infection
H. pylori is a bacterium that commonly infects the inner lining (the mucosa) of the stomach. Infection with H. pylori can cause stomach inflammation and peptic ulcers. It also increases the risk of stomach cancer, but only a small number of infected people develop stomach cancer.
Blood Type A
Studies have shown that those with this blood type have an increased risk of stomach cancer.
Smokers are more likely than nonsmokers to develop stomach cancer. Heavy smokers are most at risk.
Studies have shown that those with a history of one or more of the following are more likely to develop stomach cancer: pernicious anemia and chronic atrophic gastritis, and a adenomatous gastric polyp larger than 2 centimeters.
Poor Diet, Lack of Exercise and/or Obesity
Studies suggest that people who eat a diet high in foods that are smoked, salted, or pickled have an increased risk for stomach cancer, while those who eat a diet high in fresh fruits and vegetables may have a lower risk of the disease. A lack of physical activity may also increase the risk of stomach cancer, and people who are obese may have an increased risk of cancer developing in the upper part of the stomach.