Stomach cancer, also called gastric cancer, is caused by a malignant tumor which is formed mostly in the tissues of the stomach wall. This is a cancer that progresses slowly and that is rarely met before age 50.
More than 90% of tumors which cause stomach cancer are adenocarcinomas, that is to say they originate in the lining, the inner layer of the stomach. The tumors may eventually be extended to other layers of the stomach wall, lymph nodes and other parts of the body (liver, pancreas, colon, lungs).
Other forms of stomach cancer, such as gastric lymphoma (which affects the lymphatic system), sarcoma (which affects muscle tissue) or the gastrointestinal stromal tumor (which arises in the bodies of the tissues that support the system digestive) are much rarer. It will not be discussed in this sheet.
It is not known precisely due to stomach cancer but chronic inflammation of the lining of the stomach increases the risk. Stomach cancer is also associated with the consumption over a long period, salted, smoked or pickled, like smoking.
More stomach cancer is diagnosed early, the better the chances of recovery. When it is still limited to the mucosa of the stomach, more than 50% of sufferers will survive more than 5 years. If it has spread to the lymphatic system, in muscle layers or to other organs, the survival rate at 5 years is less than 10%.
Who is affected?
In France it is currently 7 to 8000 new cases per year. In Canada and the United States, stomach cancer is infrequent. It is even declining. In 2009, it represented less than 2% of all new cancer cases among Canadians.
Worldwide, stomach cancer still remains the second cause of cancer mortality. This type of cancer is more common in populations with precarious socio-economic conditions, which have much use of salting and smoking to preserve food. Japan, China and Chile are among the countries most affected. In industrialized countries, refrigeration has helped reduce the incidence of this cancer.