The National Cancer Institute describes the stomach as a J-shaped organ in the upper abdomen that is a component of the digestive system. When cancer develops in cells that make up this organ, it's called stomach or gastric cancer. There are different kinds of stomach cancer, depending on which layer of tissue has the cancer or whether the cancer is in supportive tissue of the stomach. Once the specific kind of stomach cancer is diagnosed, a doctor can stage it, plan treatment and make a prognosis.
Incidence and Demographics
Nearly two-thirds of people with stomach cancer are older than 65, according to the American Cancer Society, and the lifetime risk of developing the disease is one in 112.
Gastrointestinal Stromal Tumors
Gastrointestinal stromal tumors, also known as GISTs, are typically found in the stomach and supportive connecting tissue--although they can grow in other areas of the gastrointestinal tract, according to the American Cancer Society. This kind of stomach cancer is also classified as a soft tissue sarcoma, the National Cancer Institute says. GISTs develop from cells in the wall of the gastrointestinal tract called interstitial cells of Cajal, or cells that later develop into cells of Cajal. These cells are responsible for digestive system contractions when food is in the GI tract. GISTs are fairly rare, making up approximately 4,500 to 6,000 cases of stomach cancer, and not all GISTs are cancerous.
Adenocarcinoma
Adenocarcinomas make up most stomach cancers, says the American Cancer Society, comprising approximately 90 percent to 95 percent of cases. This kind of stomach cancer originates from the cells in the mucosa, which is the innermost lining of the stomach.
Lymphoma Stomach Cancers
Mucosa-associated lymphoid tissue lymphomas, or MALT lymphomas, don't start in lymph nodes, as do most of the other lymphomas. They originate in immune system tissue found in the mucosa of the stomach. MALT lymphomas make up approximately 4 percent of stomach cancers. They can be slow-growing or aggressive, according to the American Cancer Society.
Carcinoid Tumors
Gastrointestinal carcinoid tumors form in neuroendocrine cells in the gastrointestinal tract. These cells are involved in the control of releasing digestive juices and hormones, and aid in helping food travel through the GI tract, according to the American Cancer Society. This type of stomach cancer is very rare, making up only about 3 percent of stomach cancer diagnoses.
References
- American Cancer Society: What are the key statistics about stomach cancer?
- National Cancer Institute: Stomach Cancer Home Page
- American Cancer Society: What are gastrointestinal stromal tumors?
- American Cancer Society: What is stomach cancer?
- National Cancer Institute: Adult Soft Tissue Sarcoma Treatment
