What is stomach cancer?
Stomach cancer, also called gastric cancer, is a malignant tumor that develops on the lining of the stomach. Stomach cancers are classified according to the type of tissue where they originate. The most common type of stomach cancer is adenocarcinoma, which starts in the glandular tissue of the stomach and accounts for 90 to 95 percent of all stomach cancers. Other forms of stomach cancer include: lymphomas, which involve the lymphatic system; and sarcomas, which involve connective tissue such as muscle, fat or blood vessels.