Stomach cancer, also known as gastric cancer, is a malignant (cancerous) tumor within the stomach.
The stomach is a muscular sac located in the upper middle of the abdomen, just below the ribs. The stomach walls are lined with three layers of powerful muscles that mix food with enzymes and acids produced by glands in the stomach's inner lining. The stomach's delicate tissues are protected from this acidic mix by a thick, gelatinous mucus that coats the stomach lining. Food moves from the mouth through the esophagus to reach the stomach. In the stomach, the food becomes liquid. The liquid then moves into the small intestine, where it is digested even further.
Most (85%) cases of gastric cancer are adenocarcinomas that occur in the lining of the stomach (mucosa). Adenocarcinoma is a type of cancer that develops in cells lining glandular types of internal organs, such as the lungs, breasts, colon, prostate, stomach, pancreas, and cervix. Approximately 40% of cases develop in the lower part of the stomach, called the pylorus; 40% develop in the middle part, called the body; and 15% develop in the upper part, called the cardia. In about 10% of cases, cancer develops in more than one part of the organ.
Stomach cancer can spread (metastasize) to the esophagus or the small intestine, and can extend through the stomach wall to nearby lymph nodes and organs, such as the liver, pancreas, and colon. It also can metastasize to other parts of the body, such as the lungs, ovaries, and bones.
According to the National Cancer Institute (NCI), approximately 760,000 cases of stomach cancer are diagnosed worldwide and more than 24,000 cases are diagnosed in the United States each year. Men are more likely than women to develop stomach cancer. Incidence is highest in Japan, South America, Eastern Europe, and parts of the Middle East.
The American College of Gastroenterology has found that stomach cancer occurs twice as often in men and it is more common in people over the age of 55. In the United States, incidence is higher in African Americans than in Caucasians.
Cancer of the stomach is difficult to cure unless it is found at an early stage, before it has begun to spread. Unfortunately, because early stomach cancer causes few symptoms, the disease is usually advanced when the diagnosis is made. However, advanced stomach cancer can be treated and the symptoms can be relieved.
Anastomosis, adenocarcinoma, carcinoid tumors, cardia, chemotherapy, cholecystitis, computerized tomography, CT, esophagitis, fecal occult blood test, gastrectomy, gastritis, gastrointestinal stromal tumors, gastroscope, GISTs, H. pylori, Helicobacter pylori, lymphomas, magnetic resonance imaging, MALT, metastasize, MRI, mucosa-associated lymphoid tissue, nitrates, nitrites, osteoporosis, pernicious anemia, PET, positron emission tomography, pylorus, upper endoscopy.
types of stomach cancer
The great majority of stomach cancers are adenocarcinomas, which start in the glandular cells in the stomach's inner-most lining. Adenocarcinomas account for about 95% of all stomach cancers.
Lymphomas: Lymphomas are cancers of the immune system tissue in the stomach wall. Some lymphomas grow fast, whereas others grow much more slowly. Aggressive lymphomas, known medically as mucosa-associated lymphoid tissue (MALT) lymphomas, usually stem from H. pylori bacterial infection and are often curable when found in the early stages.
Carcinoid tumors: A small percentage of stomach cancers are slow growing tumors that originate in the stomach's hormone-producing cells. Carcinoid tumors tend to grow less quickly and spread (metastasize) less frequently than adenocarcinomas.
Gastrointestinal stromal tumors (GISTs): Gastrointestinal stromal tumors (GISTs) are rare tumors developed from cells called interstitial cells of Cajal. Interstitial cells of Cajal are part of the autonomic nervous system and trigger gut contraction. The autonomic nervous system consists of the nerves in the part of the nervous system that regulate non-conscious body functions, such as heart rate, blood pressure, and intestinal function.
Although GISTs can occur anywhere from the esophagus to the rectum, most are found in the stomach. Approximately 5,000 GISTs are diagnosed each year in the United States, and they occur most commonly in the stomach (60-70%) and small intestine (20-30%). The remaining cases affect the large intestine and esophagus. Most GISTs occur in people 40-80 years old, and GIST is more common in men than in women. There are no known risk factors for GIST; however, there appears to be a small increase in risk of developing GIST if there is a family history of the disease.
Recurrent cancer: Recurrent cancer can occur in individuals in remission from gastric cancer. Recurrent cancer means that although the individual's tumor was either partially or completely eliminated by treatment and was no longer detectable using diagnostic testing, a few cancer cells may not have been completely destroyed, allowing for these cells to multiply and return as a new tumor.