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General Information About Gastric Cancer
Gastric cancer is a disease in which malignant (cancer) cells form in the lining of the stomach.
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 stomach and esophagus are part of the upper 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. Gastric cancer begins in the cells lining the mucosal layer and spreads through the outer layers as it grows.
Stromal tumors of the stomach begin in supporting connective tissue and are treated differently from gastric cancer. See the PDQ summary on Adult Soft Tissue Sarcoma Treatment for more information.
For more information about cancers of the stomach, see the following PDQ summaries:
- Unusual Cancers of Childhood
- Stomach (Gastric) Cancer Prevention
- Stomach (Gastric) Cancer Screening
Age, diet, and stomach disease can affect the risk of developing gastric cancer.
Anything that increases your risk 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. People who think they may be at risk should discuss this with their doctor. Risk factors for gastric cancer include the following:
- Having any of the following medical conditions:
- Helicobacter pylori (H. pylori) infection of the stomach.
- Chronic gastritis (inflammation of the stomach).
- Pernicious anemia.
- Intestinal metaplasia (a condition in which the normal stomach lining is replaced with the cells that line the intestines).
- Familial adenomatous polyposis (FAP) or gastric polyps.
- Eating a diet high in salted, smoked foods and low in fruits and vegetables.
- Eating foods that have not been prepared or stored properly.
- Being older or male.
- Smoking cigarettes.
- Having a mother, father, sister, or brother who has had stomach cancer.
Possible signs of gastric cancer include indigestion and stomach discomfort or pain.
These and other symptoms may be caused by gastric cancer. Other conditions may cause the same symptoms.
In the early stages of gastric cancer, the following symptoms may occur:
- Indigestion and stomach discomfort.
- A bloated feeling after eating.
- Mild nausea.
- Loss of appetite.
- Heartburn.
In more advanced stages of gastric cancer, the following symptoms may occur:
- Blood in the stool.
- Vomiting.
- Weight loss for no known reason.
- Stomach pain.
- Jaundice (yellowing of eyes and skin).
- Ascites (build-up of fluid in the abdomen).
- Trouble swallowing.
WebMD Public Information from the National Cancer Institute
This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http://cancer.gov or call 1-800-4-CANCER
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