What Causes It The exact cause is unknown, but most gastric cancers are believed to be caused by carcinogens, with diet as a major factor. Nitrites found in smoked meats, fish and other foods and the nitrates used as food preservatives have been implicated, along with aflatoxin, a carcinogenic fungus contaminant that is present in some foodstuffs such as peanuts.
Various medical conditions are also associated with the development of stomach cancer. A history of or the presence of a Helicobacter pylori infection may lead to stomach inflammation that can induce mutations and DNA damage. This may deactivate suppressor genes and may lead to cancer. The lack of acid in stomach secretions (achlorhydria), for example, means that the bacteria responsible for converting nitrates to carcinogenic nitrosamines are not destroyed. About 5 to 10 percent of people with pernicious anemia will develop gastric cancer. And the chronic backup, or reflux, of stomach acids into the esophagus can irritate the glandular tissue at the junction of the stomach and esophagus, which may lead to cancer. Gastric polyps are another possibility, since they may become malignant .
