Stomach cancer, also called gastric cancer, begins when cells in the stomach start to grow out of control. Gastric cancer is a disease in which malignant (cancer) cells form in the lining of the stomach. Stomach cancer is an abnormal growth of cells that begins in the stomach. 

Age, diet, and stomach disease can affect the risk of developing gastric cancer. Though the actual cause of stomach cancer is not yet known, there are some factors associated with it, particularly diet and lifestyle. For example, a diet high in smoked or salted foods and processed meat and low in vegetables is a risk factor for stomach cancer, as is drinking alcohol and smoking.

There may be no symptoms of stomach cancer early on. Later, symptoms include feeling bloated after eating, feeling full after eating small amounts of food, nausea, heartburn or indigestion.