Stomach cancer, also called gastric cancer, is the malignant growth of cells in the stomach that can eventually invade the surrounding healthy cells. Stomach cancer often begins in the innermost lining of the stomach and metastasizes (spreads) outside of the stomach to the surrounding lymph nodes and organs. In more advanced stages, the cancer cells can spread to organs such as the lungs, liver, pancreas, colon, bones and ovaries in women.

The stomach is a sac-like organ located in the abdomen beneath the diaphragm and above the intestines that collects food and liquids after they travel through the esophagus. It is within the stomach that gastric juices mix with the food as part of the digestive process. The stomach is made of five layers.  The five layers of the stomach are:

• Mucosa. Innermost layer where cancer typically first appears. Stomach acid and gastric enzymes are produced by the glands in this layer.
  
  
• Submucosa. This layer supports the mucosa.
  
  
• Muscularis. This layer is comprised of muscles that move the stomach during the digestive process.
  
  
• Subserosa. The outer “wrapping” layer.
  
  
• Outermost serosa. The outermost layer that protects the inner layers.

Stomach cancer usually begins in the innermost layer (mucosa) and then enters into the outer layers as the malignant cells grow and spread. While there are four main types of stomach cancer, adenocarcinoma is by far the most common, making up 90 to 95 percent of stomach cancer cases according to the American Cancer Society (ACS).

The ACS predicts that about 22,280 Americans will be diagnosed with stomach cancer in 2006. It occurs twice as often in men as in women and two-thirds of cases are found in people 65 years of age and older. The disease was once more common in the United States and was a leading cause of cancer deaths. Improved handling and storage of foods is thought to have contributed to its decline in the United States. Some physicians also believe the increased use of antibiotics to treat infections in children may be related to the lower incidence of the disease.

However, stomach cancer remains more common in some other countries in the world. The higher incidence may be related to less hygienic conditions and poorer refrigeration, which can lead to bacterial infections linked to the disease. In addition, many of these countries each large amounts of foods that are preserved by pickling or smoking – factors that are associated with stomach cancer.

In 2006, the ACS estimates that 11,430 people in the United States will die from stomach cancer. The overall 5-year survival rate for Americans with stomach cancer is 23 percent. If the cancer is detected in the early stages, the 5-year survival rate increases to 60 percent. The prognosis also depends on the location of the cancer. Individuals with cancer in the upper portion of the stomach may have a poorer chance of survival than those with the disease in the distal or lower portion of the stomach.

Stomach cancer is difficult to detect in the early stages because there may be few or no symptoms. For this reason, the overall survival rate for this cancer has not significantly improved during the past 15 years. As with most cancers, prognosis for survival improves with early detection and treatment