What is stomach cancer?
Stomach cancer, also called gastric cancer, is a cancer that starts in the stomach.
Stomach cancer should not be confused with other cancers that can occur in the abdomen, like cancer of the colon (large intestine), liver, pancreas, or small intestine because these cancers may have different symptoms, different outlooks, and different treatments.
Development of stomach cancer
Stomach cancers tend to develop slowly over many years. Before a true cancer develops, pre-cancerous changes often occur in the inner lining (mucosa) of the stomach. Cancers starting in different sections of the stomach may cause different symptoms and tend to have different outcomes. The cancer’s location can also affect the treatment options.
Stomach cancers can spread (metastasize) in different ways. They can grow through the wall of the stomach and invade nearby organs. They can also spread to the lymph vessels and nearby lymph nodes. Lymph nodes are bean-sized structures that help fight infections. The stomach has a very rich network of lymph vessels and nodes. As the stomach cancer becomes more advanced, it can travel through the bloodstream and spread to organs such as the liver, lungs, and bones.
Types of stomach cancers
Different types of stomach cancer include:
Adenocarcinoma
About 90% to 95% of cancers of the stomach are adenocarcinomas. When the term stomach cancer or gastric cancer is used, it almost always refers to an adenocarcinoma. These cancers develop from the cells that form the innermost lining of the stomach (known as the mucosa).
Lymphoma
About 4% of stomach cancers are lymphomas.
Gastrointestinal stromal tumor (GIST)
These are rare tumors that start in very early forms of cells in the wall of the stomach called interstitial cells of Cajal.
Carcinoid tumors
These are tumors that start in hormone-making cells of the stomach. Most of these tumors do not spread to other organs. About 3% of stomach cancers are carcinoid tumors.
Other cancers
Other types of cancer, such as squamous cell carcinoma, small cell carcinoma, and leiomyosarcoma, can also start in the stomach, but these cancers are very rare.
Source: cancer.org
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