Stomach cancer is a disease in which cancer cells grow in the stomach. Stomach cancer can develop in any part of the stomach and spread to other organs through tumor growth, the bloodstream, or the lymphatic system.

There are five layers of tissue in the stomach. The innermost layer is called the mucosa and is where approximately 90% to 95% of stomach cancer begins. This type of tumor is called an adenocarcinoma.

Less common stomach cancers include:

  • Lymphoma—a cancer of the immune system; sometimes found in the stomach wall
  • Gastric stomal tumors—tumors of the stomach wall
  • Carcinoid tumors—tumors of the hormone-producing cells of the stomach

It is believed that stomach cancer takes several years to develop. Many precancerous changes that rarely cause symptoms occur before stomach cancer develops. This is why most cases of stomach cancer are undetected until the later stages of the disease.

Stomach Cancer
Stomach cancer
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The exact cause of stomach cancer is not known. There are, however, several well-known risk factors that contribute to the development of stomach cancer.