The stomach is a J-shaped organ in the upper abdomen. It is part of the digestive system, which processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) in foods that are eaten and helps pass waste material out of the body. Food moves from the throat to the stomach through a hollow, muscular tube called the esophagus. After leaving the stomach, partly-digested food passes into the small intestine and then into the large intestine.
The esophagus and stomach are part of the upper gastrointestinal (digestive) system.
The wall of the stomach is made up of 3 layers of tissue: the mucosal (innermost) layer, the muscularis (middle) layer, and the serosal (outermost) layer. Stomach cancer begins in the cells lining the mucosal layer and spreads through the outer layers as it grows.
See the following PDQ summaries for more information about stomach cancer:
Stomach cancer is not common in the United States.
Stomach cancer is less common in the United States than in many parts of Asia, Europe, and Central and South America. Stomach cancer is a major cause of death in these parts of the world.
In the United States, the number of new cases of stomach cancer has greatly decreased since 1930. The reasons for this are not clear, but may have to do with better food storage and changes in the diet, such as lower salt intake.
Older age and certain chronic conditions increase the risk of stomach cancer.
Anything that increases the chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk to your doctor if you think you may be at risk for stomach cancer. Risk factors for stomach cancer include the following:
- Having any of the following medical conditions:
- Helicobacter pylori (H. pylori) infection of the stomach.
- Chronic gastric atrophy (thinning of the stomach lining caused by long-term inflammation of the stomach).
- Pernicious anemia (a type of anemia caused by a vitamin B12 deficiency).
- Intestinal metaplasia (a condition in which the cells that line the stomach are replaced by the cells that normally line the intestines).
- Polyps in the stomach.
- Familial adenomatous polyposis (FAP).
- Hereditary nonpolyposis colon cancer (HNPCC).
- Having a mother, father, sister, or brother who has had stomach cancer.
- Having had a partial gastrectomy.
- Eating a diet high in salted, smoked foods or low in fruits and vegetables.
- Eating foods that have not been prepared or stored the way they should be.
- Smoking cigarettes.
The risk of stomach cancer is increased in people who come from countries where stomach cancer is common.