Stomach cancer, also called gastric cancer, which develops in the stomach. 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. These early changes rarely cause symptoms and therefore often go undetected.
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 comes to advanced stage, it can travel through the bloodstream and spread to organs such as the liver, lungs, and bones. If cancer has spread to the lymph nodes or to other organs, the patient’s outlook is not as good.
Types of stomach cancers
Adenocarcinoma
About 90% to 95% of cancers of the stomach are adenocarcinomas. These cancers develop from the cells that form the innermost lining of the stomach (known as the mucosa).
Lymphoma
These are cancers of the immune system tissue that are sometimes found in the wall of the stomach. About 4% of stomach cancers are lymphomas. The treatment and outlook depend on the type of lymphoma.
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. Some of these tumors are non-cancerous (benign); others are cancerous. Although GISTs can be found anywhere in the digestive tract, most are found in the stomach.
Carcinoid tumor
These are tumors that start in hormone-making cells of the stomach. Most of these tumors do not spread to other organs.