Gastric cancer, or cancer of the stomach, is the second most common cause of death due to cancers worldwide. About 95% of gastric cancers are adenocarcinomas. Other forms seen rarely include lymphomas, carcinoid tumors, and gastrointestinal stromal tumors. Infection of the stomach with Helicobacter pylori is the most important risk factor for the development of this disease, since infection may lead to pre-cancerous changes in the gastric lining. The condition may be aggravated by eating foods high in salt and low in fiber, smoking, and consumption of alcohol. Unfortunately, since the initial clinical features of the condition are very similar to other less serious disorders, such as peptic ulcers, most patients report the illness and are diagnosed at a late stage of the condition. Usual features of gastric cancer include abdominal discomfort, indigestion and heartburn, internal bleeding visible in the stool, vomiting blood, and anemia and associated fatigue. This condition is more pronounced in Asian countries like Japan, China, and Korea, where it is the leading cause of mortality. This could be due to the high amount of salted, pickled, and smoked food in the diet of these regions. In addition, the condition is slightly more common in men than in women.

Initial diagnosis may include an upper endoscopy and/or a stomach X-ray with a barium swallow. Confirmation is based upon findings of CT/MRI scans. Any spread of the cancer to the lungs needs to be checked with a pulmonary X-ray. Similarly, the presence of tumor markers, such as carcinoembryonic antigen, in the blood may be checked for, to estimate the extent of metastasis, if any. The most common treatment method for gastric cancer is surgical resection of the affected tissue. Some surrounding tissue as well as lymph nodes may also need to be removed. This is usually followed up by chemotherapy and/or radiation therapy. Antibiotics may also be used in individuals infected with H. pylori. Prognosis is largely dependent upon the stage of the cancer at the time it is first diagnosed. The 5-year survival rate after surgical resection is 30-50% and 10-25% for patients diagnosed at stage II and III, respectively. The management of families with hereditary diffuse gastric cancer is challenging as screening for cancer in CDH1 mutation carriers is insufficiently sensitive and the commonly recommended option, prophylactic total gastrectomy, is associated with certain morbidity and even potential mortality.

As in all cancers, gastric cancer also manifests itself due to changes in the genetic structure of cells, causing them to over-multiply. Mutations in various genes have been implicated in the development of stomach cancer. Some of these are the APC gene, Interferon Regulatory Factor 1 (IRF1), Kruppel-Like Factor 6 (KLF6), MUTYH, KRAS, Caspase 10, Oncogene ERBB2, and Fibroblast Growth Factor Receptor 2 (FGFR2). Most interestingly, it has been noted that about 10% of gastric cancers are familial in origin. The most well-studied of these cases have shown germ-line mutations in the E-cadherin (CDH1) gene, resulting in an autosomal dominant and highly penetrant form of the condition.

As in all cancers, gastric cancer also manifests itself due to changes in the genetic structure of cells, causing them to over-multiply. Mutations in various genes have been implicated in the development of stomach cancer. Some of these are the APC gene, Interferon Regulatory Factor 1 (IRF1), Kruppel-Like Factor 6 (KLF6), MUTYH, KRAS, Caspase 10, Oncogene ERBB2, and Fibroblast Growth Factor Receptor 2 (FGFR2). Most interestingly, it has been noted that about 10% of gastric cancers are familial in origin. The most well-studied of these cases have shown germ-line mutations in the E-cadherin (CDH1) gene, resulting in an autosomal dominant and highly penetrant form of the condition.