Gastric cancer (stomach cancer) is the second most common type of cancer in the world. Most cancers of the stomach arise in the antrum,which is the lower third of the stomach,near the duodenum. There are different kinds of stomach cancers, depending on the type of cells from which the cancer arises. Cancers that form in the stomach’s secretory glands are called adenocarcinomas; these are the most common form, accounting for more than 90 percent of all stomach cancers. Other types are sarcomas (cancers of the stomach’s muscle layer), and gastric lymphomas, which form in certain immune cells (B and T cells) of the stomach tissue. Adenocarcinoma of the stomach is strongly associated with H.pylori infection.Recent studies of patients with stomach cancer have revealed that over 90 percent of people who develop adenocarcinoma of the stomach have H. pylori infections. So, what is it about H. pylori that predisposes certain people to develop cancer? A recent theory on the development of stomach cancer revolves around the interaction between the H. pylori organism itself and the infected person’s own immune response.