Your stomach is a J-shaped organ in the upper abdo...

Your stomach is a J-shaped organ in the upper abdomen where digestion begins before food is passed to your intestines. Cancer can arise in any part of the stomach, and is believed to develop slowly over many years. Stomach cancer -- also referred to as gastric cancer -- is usually preceded by precancerous changes in the stomach lining, although these changes rarely produce symptoms. Because stomach cancer often does not cause symptoms until it is quite advanced, it is not often detected in its earliest stages. Most stomach cancers (90 to 95 percent) are classified as adenocarcinomas. Other types of stomach cancer include squamous cell carcinoma, lymphoma, stromal tumors (cancer of the muscle or connective tissue of the stomach wall), and carcinoid tumors (cancer of the hormone-producing cells of the stomach).