The document summarizes the stomach and stomach cancer. It describes the stomach's location between the esophagus and small intestine. It explains how the stomach breaks down food using gastric acid, pepsin, and other enzymes. Parietal cells secrete intrinsic factor to enable vitamin B12 absorption. Stomach cancer causes include smoking, salty fish, and bacteria. Surgery is a common treatment that may involve removing part or all of the stomach, and sometimes part of the intestine.